Interview with Mary Stopes-Roe


Interview with Mary Stopes-Roe


Discusses her father’s designs work and remembers both skipping stones on a river during holidays with her father and catapulting marbles over a washtub in their garden. She goes on to discuss the Eder Möhne and Sorpe operation, the bouncing bomb and the Tall boy and Grand Slam bombs. She talks about the importance of Roy Chadwick and the Lancaster, and her father’s other designs that included the R100 airship, the geodetic structure of the Wellington, and designs for civil aircraft the Wild Goose and the Swallow.




Temporal Coverage

Spatial Coverage




00:23:12 audio recording

Conforms To


This content is available under a CC BY-NC 4.0 International license (Creative Commons Attribution-NonCommercial 4.0). It has been published ‘as is’ and may contain inaccuracies or culturally inappropriate references that do not necessarily reflect the official policy or position of the University of Lincoln or the International Bomber Command Centre. For more information, visit and





AP: This interview is being conducted for the International Bomber Command Centre. The interviewer is Andrew Panton. The interviewee is Mary Stopes Roe. The interview is taking place at Mrs Stopes Roe’s home in Birmingham on the 30th of May 2015. Mrs Stopes Roe is the daughter of Sir Barnes Wallis the English scientist, engineer and inventor.
MSR: All through the 30s we used to go on wonderful camping holidays down to Dorset. The Isle of Purbeck. And my father, they were lovely holidays, he was such fun on those holidays. And one of the games that we played there was skipping pebbles across the water, you know. As one does. Or some people do. Anyway, he used to skip pebbles across the water and he could get his to do eight or nine or something or other. I never could do it. It’s that flick of the, twist of the wrist which I never got and mine used to go plop and plop and down. But it was great fun, you know. That, I mean of course it isn’t exactly straightforwardly linked to the bouncing bomb but it was something that was in our background. And my father asked us four, well he told us four, to collect my mother’s old tin wash tub, to fill it with cold water which we brought out in cans and things from the kitchen and poured into the washtub. And it was placed on the garden table and then my father produced a catapult which he’d had made at the works and he borrowed my sisters’ marbles and he [laughs] he shot the marbles over the water in the water tub. And there were, there was a string spread across the water tub. And my brother who was the eldest and the most clever had to say whether the bobber went under or over the string and how many times it bounced going across the tub. And the rest of us stood and watched just thinking that daddy was playing a nice game. And then our job was to find the marbles when they’d dropped off the other side. The dear old family doctor who’d come up for reasons, I think my mother was worried about — I don’t know what she was worried about but anyway he was such a dear old friend he came a lot. And he stood in the background and there he is in the picture. My mother, who was very snap happy with her little Kodak thing, photographed everything that happened and she photographed that. And there we all are for time until eternity. Standing by the wash tub on the garden terrace. And my mother later reported that we children were all there of course and when, when the, when the raid was public knowledge my mother reported of course the children never said anything. Thinking that we were very virtuous. I mean she put about the idea that we were very virtuous and, you know, careful. Actually, of course, what really happened was we didn’t say anything was because we had no idea why he was playing this jolly game in the garden. And if you say to your friends when you’re sort of thirteen fourteen’ish, ‘Well my father bounced marbles on the water tub in the garden.’ I mean, you don’t do you because it sounds so stupid. So of course, we didn’t say anything. But the minute the raid was reported I realized what that was for. Roy Chadwick’s contribution, apart from designing the Lancaster, which is no mean feat anyway was absolutely critical to the whole raid. My father realized this and he wrote very warmly to Chadwick to thank him for the effort he made in altering the bomb bay of the Lancaster. Without which alteration the bomb couldn’t be carried and therefore no raid. That was never, I don’t think, I know he didn’t think that Chadwick had had enough honour and, and fame for, for what he did. And I certainly don’t think he did. I mean, when does he ever get mentioned? And yet without him there would not have been a raid, which my father knew and he, and he expressed his gratitude and admiration. The whole of that alteration was done on twenty Lancasters, I think in under three weeks or something. I mean, amazing. Well having altered the Lancaster, poor old Lancaster’s undercarriage to carry the upkeep. The bouncing bomb. Then of course my father designed the earthquake bombs — Tallboy and Grand Slam. A Tallboy is pretty big. A Grand Slam is even bigger and the Lancaster had to have her undercarriage altered again. Her bomb bays. In fact, in the Grand Slam, I think I’m right, that the bomb bay couldn’t actually be used. It had to be sort of tied up with rope. Not quite but when it came to Grand Slam, twenty two thousand pound of bomb underneath the Lancaster’s belly Roy Chadwick had to remove the bomb doors completely and attach the Grand Slam under her belly by means of chains. I mean, that was no mean alteration but it worked. And my father is remembered, mainly I suppose, for the bouncing bomb for the dams’ raid. For the engineer’s way of stopping the war which is wonderful. I don’t complain about that at all but he, it is not, he was not a man of war. He was a man of peace. He was brought up to believe very very firmly in the benefits of the society in which he lived. The culture in which he lived. The background against which he lived. And he thought it was his duty, indeed the duty of every man and woman to fight for, to protect this culture. That’s why he did it. Not because he was a man of war. He was not. Of course, you have big wars to fight and you fight them but in the mean, in between the wars he did develop the most beautiful airship, and successful, which I don’t, I don’t think people should forget. The R100. Not the R101. That’s a very interesting story that but not to be told here. But it was from the building of the R100 that he devised the geodetic structure for making curved and strong and lightweight bodies. Heavier than aircraft. That went straight into the Wellington, the Wellesley and would finally have been used in the Windsor which actually it was not used in the, in the war. I don’t think it every reached the bombing stage. So, it was really design that he was so interested in, I think. Apart from defending his family and country. Nation and belief. It was always the design. The best design that he was aiming at. After the war, in fact, before the war ended he’d moved on in his mind to civil aviation and the benefit for keeping together the Commonwealth as it, by then was. By the ability to fly all around the world without having to put down to take on whatever supplies were needed. Because the intervening lands might not be so welcoming. But this of course involved high speed which involves supersonic flight. Supersonic flight, to be achieved successfully as I have always understood it is it requires a different aeroplane. A different shape of the wings of the aeroplane. They should fold back so that it can dart through the, through the upper atmosphere without having these wings out at right angles. So, from that he started to design what was originally called the Wild Goose. In 1948 he started, well he was thinking of it before the war ended. And that is, he wrote some wonderful memoirs of that. That time. Writing actually in letters to my mother. He never wrote without having a purpose if you see what I mean. If somebody was going to read it. He never sent the letters but there they all are. First of all at Thurley old aerodrome in Bedfordshire and then down to Predannack in Cornwall. On the Lizard. And there Wild Goose turned into the Swallow which was a very beautiful aircraft with the swept back wings in high powered flight. But you have to have them in the normal position to take off in the ordinary atmosphere. So that’s the problem. He, the Swallow got to the point at which it could have had trial runs with a, with a test pilot. And his good old friend Mutt Summers and others would have been willing to try to fly the Swallow. But after the disaster, to my father’s mind, indeed quite true, of the deaths of so many brave young men in the dams’ raid he swore that never again would he put another man’s life in danger. He would not have a test pilot. So, and as everybody knows the government wouldn’t support the development any further and so as he sadly said, we sold it to America. What Boeing did with it I can’t remember. But anyway, my father sadly said as I also remember they spoiled it by putting a tail on it. There was a plan. He devised a design for a bridge to go, I think it was underwater. An underwater bridge over the Messina Straits between Italy and Sicily. I don’t quite know what happened to that design but I don’t think it ever got made. Which was a pity because it would have been, you know, rather interesting. He, he designed racing skiffs for boys clubs. That was his love. His love of the water and everything to do with the sea. So, when somebody asked him to do that he did it. He designed at Brooklands where he was working of course for, by this time it was BAC not Vickers Armstrong’s and the stratosphere chamber is absolutely huge. I have, in fact, I it was opened, it was redone by English heritage and opened again about a year ago. And it is there by the, by where he had his research and development department. And in it you could test anything that you wanted to have, wanted to be tested under extreme circumstances. For example, de-icing of trawlers and indeed de-icing of aeroplane structures too in very high altitudes. And there are wonderful photographs of trawlers with, in the stratosphere chamber, ice dripping off their rigging and all this and whatever. It’s amazing. That was his design and there it still is. So that, that was another thing that was quite important. While the Swallow was being developed and perfected in Predannack in Cornwall Leonard Cheshire joined Barnes Wallis again there. I think this is not very often remembered that that was a point at which the two worked together again and my father admired Cheshire very much indeed. I expect Cheshire admired him but that I don’t know because he was very interested in Cheshire’s work for the disabled, the sick and the needy and was a great supporter of the Cheshire homes. Always. And that’s not very often, I think, remembered. On that same line my father devised, he became the first president of the Bath Medical Engineering Institute and he, because he had designed lightweight calipers for children. You know, he had seen children hobbling about with great hefty things on, calipers on their legs and he designed lightweight calipers. And thus, he became the President of Bath Medical Engineering Institute which was a position which he held for quite some years. I’ve often wondered what it was that made him even think of, you know, sort of a bit far from bombs and flying at supersonic speeds. But looking back over his life his father, who was a doctor, got polio myelitis in 1893. And my father was then six and I mean, it was a pretty, it was a crisis for the family because of course at that stage there was no cure. He just was laid flat for six months. Money was scarce and so on. And in the end my grandfather had an enormous metal caliper down his leg. And I remember, as a child we used to wonder what on earth was under his trouser leg because it had this very sort of rigid angle at the knee and when he wanted to bend his leg he had to bend down and press the metal and it made a click and we were fascinated. But I suspect the trouble the family went through then stuck in Barnes’s mind for the rest of his life. One of the outcomes of the raid on the dams was that precision bombing became a possibility which it had not been before. You did not have to have carpet bombing once you had got a squadron with the skill and aptitude of 617. And they were amazing. You could actually precision bomb without damaging vast numbers of ordinary civilians. This was very important. My father had, had it in mind and the Tallboy and Grand Slam were on his drawing board but of course they couldn’t be used without the efficiency and skill and bravery of 617. So that the two were totally, totally linked. The development of the skill and competence of the squadron and the skill of the designer. One outcome of the dams’ raid, the success of the dams’ raid which is not often mentioned I think is the vital importance of precision bombing which 617 Squadron achieved. Previously, while of course there were many targets that would have benefited us greatly if we could have smashed couldn’t be broken by ordinary sized bombs and dropped from a great height. To do, to smash the really heavy armaments construction places in France and North Europe you needed things like the Tallboy and the Grand Slam. The earthquake bombs which my father had certainly begun to design. I don’t know how far he’d got by the time the dams’ raid was achieved but of course they, they were not any use without the capability for precision bombing which 617 had now achieved. Once the Air Ministry, War Ministry had realized this, that there was this ability to deliver a weapon. They did say to my father, you know, finish designing the earthquake which he then went and proceeded to do. And it was, I mean that the, the development of the precision bombing capability is not always, I think, given the merit that it should have been given. Those men were extremely skilled. Without their ability and of course the bomb. The tools to go to be used. The bombs. The earthquake bombs. The Tirpitz would not have been sunk. The first target to be hit by an earthquake bomb was the Saumur Tunnel. That was the Tallboy. Tallboy then went on to crack the V1 bomb launch sights. I remember those. They were famous. They came over. They made a droning noise. When you heard the droning noise you just were pretty near it, pretty careful to listen. If the droning noise stopped you were in trouble. Get under the kitchen table or something of the sort. But if the droning noise went on you were alright. It was somebody else. That was the V1s. All seen from a child’s point of view. And the other thing, the next, the next big, I think the most famous Tallboy success was where the V2 rocket was going to be. Rocket was going to be launched from. The V2 rocket was going to be launched from Northern France, a place called Wizernes, and it was from some sort of a launch. It was undercover. Under a great flat concrete surface of a depth which would be quite impossible for ordinary bombs to reach and which no amount of scatter bombing could possibly destroy. But we still have one of the 617 old boys. If I can call them that. John Bell. Who launched from, who launched a Tallboy. I don’t remember which plane. Which plane it was dropped from but —
AP: He dropped it from a Lancaster.
MSR: Oh, I know it was a Lancaster.
AP: Oh sorry.
MSR: I meant the, oh goodness me.
AP: I think it was KCA.
MSR: Was it? Oh, I’d better put that in it case it’s wrong.
AP: We’ll just say sorry about that. We’ll just keep talking. He was a bomb aimer.
MSR: Yeah.
AP: And he was the one who released that Tallboy.
MSR: Yes.
AP: On the dome.
MSR: Yes. The only way to destroy that dome was by an earthquake bomb. And John Bell, who is still with us who was the bomb aimer on the Lancaster that went over this Wizernes rocket pen and his bomb dropped on the, on this concrete dome. Lord knows how much concrete was piled in there but anyway the Tallboy destroyed it and the V2 rocket didn’t have a chance.
AP: So, they were never able to launch it.
MSR: No.
AP: Because it was in a chalk quarry, this is the interesting geology bit, it was in a chalk quarry and the dome was, there was a whole load of rockets underneath it. John’s bomb didn’t hit the dome. It just hit the outside of the dome and because it was chalk the earthquake shockwave crumbled the chalk.
MSR: Yeah. Yeah. This rocket, V2 rocket pen was actually constructed within a chalk quarry. A quarry for mining chalk and while my father had always said that if you could get a bomb into the, down into the earth deep enough it didn’t have to be actually on the spot because the earthquake effect would destroy the target that you were aiming at. I remember him saying that if it would, if water could increase the strength of an explosion at thirty feet then if you could only get a bomb down in the earth at sufficient depth the same sort of earthquake effect would, would work. And it did. And because it was in this chalk quarry the chalk all shook and crumbled and the whole thing collapsed. But it was the earthquake effect. Not having gone straight down through the concrete surface. But that was what my father had predicted would happen. He would get a bomb deep enough into the earth which the Tallboy did and the Grand Slam even more.



Andrew Panton, “Interview with Mary Stopes-Roe,” IBCC Digital Archive, accessed December 1, 2023,

Item Relations

This item has no relations.