In June 1943 after the Investiture ceremony for 617 Squadron at Buckingham Palace for their involvement in Operation Chastise, a dinner was held at the Hungaria Restaurant, London, given by the A.V. Roe & Company ( Avro ) which built the Avro Lancaster. The photograph was signed at the dinner and Wg Cdr Guy Gibson is photographed signing his name on the centre. Later photos of Sir Barnes Wallis show the Dam photos hanging in his office. Signatures include :- Wg Cdr Guy Gibson Fg Off Edward C Johnson Flt Sgt George A Deering Plt Off Lance Howard Fg Off Harold S Hobday Flt Sgt Len J Sumpter Flt Lt Harold Wilson Roy Chadwick Henry Albert “Sam†Brown Mutt Summers Flt Lt R D Trevor-Roper DFM Plt Off Harlo Taerum Flt Lt Jack Leggo Flt Lt Joe C McCarthy DFC, RCAF Flt Sgt D A MacLean Flt Lt David J H Maltby DFC Plt Off John Fort Sgt Vivian Nicholson Flt Sgt Tammy Simpson RAAF Cliff Caple (Armt) Plt Off Frederick Spafford Flt Lt Bob Hay Flt Sgt George Powell Sgt John Pulford Sgt Jim Heveron Sgt Taylor Sgt J L H Cammack (Electrician - Ground staff) Flt Lt Harry Humphries Flt Lt Les Munro