136 A collection of marbles belonging to Sir Barnes Wallis' daughter, Elisabeth Gaunt (now 93). These marbles were famously used by Wallis during his garden experiment in April 1942 whilst developing the conceptual principles behind the Dam Busters 'bouncing bomb'. Of the day Elisabeth recalls "I remember the Easter bank holiday weekend when Daddy came home with a strange device and placed it in front of a metal wash tub that he had filled with water in the garden. He then asked if he could borrow my marbles for an experiment. I was fiercely protective of my marbles but reluctantly agreed, I was very worried in case any of my precious marbles were lost, sadly some of them did get chipped." Elisabeth's late sister Mary Stopes-Roe, also reflected on these formative experiments, recalling "We had this wonderful experiment at our family home, where my father set up the washtub and got a catapult made by his department. He altered the angle of the slant at which the ball was delivered and the distance from the water, and then he bounced my sister's marbles, which she has never forgotten, the fact that they were her marbles." Mrs Gaunt has displayed the marbles over the years at various events and they have always been in her possession.

144 A pair of cross section plans of the Mohne Dam to illustrate the intended path of the Upkeep mine stencilled "CROSS SECTION OF THE MOHNE DAM" and "CROSS SECTION OF THE UPPER PART OF THE DAM". The main dam plan displaying a blue mine against the dam freeboard and another example of the red mine further down at 30 metre depth (the detonation point). The water has been added with a cumbersome blue crayon/pencil, the torpedo nets indicated by a yellow crayon buoy. At the top of the plan is a pencilled skimming bounce motion and there are pencilled formulae to the centre of the plan. A label bottom right stating Dr. Barnes Wallis used the plan to brief 617 Squadron on the night of the raid. Plan framed 83cm h x 109cm w (unframed x 73cm h x 100.5cm) The upper dam plan details a close up view of the mine striking the freeboard of the dam, the water side in coloured blue crayon, and then another depiction of a red mine at 30 metres depth - a light red pencil indicates 'detonation depth'. Plan framed 82cm h x 94cm w, (73cm h x 84.5cm w unframed) Both plans label to verso "loaned to RAF Museum by Sir Barnes Wallis" together with RAF stock label circa 1971.

150 Two black and white oak framed aerial photographic prints of the Mohne Dam before and after the Operation Chastise 'Dam Busters' strike on May 16th 1943, the post strike photograph signed by surviving members of 617 Squadron also ground crew and admin staff, notably Wg Cdr Guy Gibson V.C DSO DFC whose signature is direct centre over the water rushing through the breach in the dam. 105cm h x 105cm w (89.5cm h x 89.5cm w unframed)

140 A 2 inch aluminium sphere of the type used in the Teddington ship tanks during the development of the Golf Mine 'bouncing bomb'. Discovered in a box of Sir Barnes Wallis' lectures slides on the 'Dam Busters' raId, the spheres were the next evolutionary step after the garden marbles leading eventually to the development of the Highball and Upkeep bombs. Between 9 June and 10 September 1942, Wallis made use of one of the two large indoor water tanks of The National Physical Laboratory at Teddington on at least 18 occasions, he stated "I moored a wax model of a battleship several hundred feet up the tank, broadside on. We fired 2in diameter balls at it, when of course after hitting the freeboard of the ship, the sinking velocity of the ball combined with back-spin to move it towards the ship, and by adjusting the mean density of the ball we were able to pass it right underneath 'the soft underbelly', to quote Winston Churchill

314 A grey Simplon draughting table/desk, c.1960s, fitted with a Mavitta Master 360 draughting machine. The conical cast-iron base was manufactured by Dargue Brothers at Simplon Works, Halifax, and features a central red Simplon logo, pedals, and rubber footrests. The base supporting a pine table top with attached draughting machine. Together with a revolving steel high chair by ROC Birmingham

49 Alfred Egerton Cooper R.B.A. (British, 1883-1974) - HMA 9 Airship in Flight over Norfolk, oil on canvas, signed and dated 1917 recto, Bourlet label verso, 58cm h x 89cm w, within a painted wood frame. Provenance: Sir Barnes Wallis thence by descent. Exhibited: possibly "Airships in Peace and War"? Prince's Gallery, Knightsbridge, September 1919. The No 9 was the first airship Barnes Wallis worked on as an assistant at Vickers with Chief Designer H B Pratt and the first British airship to fly. A E Cooper and Barnes Wallis were close friends and Cooper is thought to have gifted the picture to Wallis. The painting likely depicts flight over Norfolk as the Airship was stationed from October 17th 1917 at Royal Naval Air Service Station Pulham (later RAF Pulham). The painting is clearly visible in many publicity photographs of Wallis in his office.

135 A wooden adjustable catapult designed for and used in the 1955 movie "The Dam Busters" by Michael Redgrave (playing Sir Barnes Wallis). The catapult represents that used by Wallis in his 1941 April Bank holiday garden marble experiments, to prototype the concept of the bouncing bomb. The catapult raised on triform base and mounted on metal collar with tripod supports. The catapult firing rail adjustable in angle by a wing nut, having a projectile receptical attached to elastic cord running along the top rail of the device. The rail fitted a trigger to release the projectile. 138cm h, catapult rail 93cm l

404 A pair of Sir Barnes Wallis circular tortoiseshell effect framed glasses circa 1940/50s, Wallis can be seen wearing these glasses in a promotional photo for "The Dam Busters" 1955 film alongside Michael Redgrave (one lens is loose).

143 A 1942 A5 calendar notepad by Napier bound in marbled green calf initialled in gilt B.N.W, half empty with top sheet having pencilled diagrams of what appears to be a tunnel (or support structure of Italian dams) with dimensions having a round object following a dotted curve. One other loose sheet having technical drawing of and circular diagrams

1 Alfred Egerton Cooper R.B.A. (British, 1883-1974) - Half Length Portrait of Barnes Wallis in Army Uniform smoking a Pipe, oil on canvas, signed with initials, 32cm h x 23cm w. Provenance: Sir Barnes Wallis thence by descent. Note: this work was most likely painted in 1915, while Cooper and Wallis were serving in the Artist Rifles.

38 A piece of notepaper by Sir Barnes Wallis detailing calculations of airship fuel requirements for a 16 day round trip written in red ink with diagram verso, together with the 1924 Engineer Yearbook (split in half, loose boards and pages) within which it was found. 2905pp. 31st Edition. Yearbook signed B.N. Wallis to first page