109 Squadron RAF flying Avro Anson and Vickers Wellington aircraft it was engaged during the next two years in development of radio counter-measures and also new radar aids, notably the blind bombing system known as Oboe later used so successfully by the Pathfinder Force.

At 1830 on the evening of 5 November 1941 Bull took off in a Wellington Mark Ic bomber (serial number T2562) from Boscombe Down on a Special Duties mission to investigate the capabilities of the German radar chain sites along the west coast of France.

Unable to continue Bull held the aircraft level while his crew of five baled out and then followed himself being taken prisoner on landing by parachute in France.

667[10][11] where he made himself a general nuisance to the German guards (a popular pastime amongst bored RAF prisoners) and there he brewed illegal potato skin alcohol for Christmas celebrations.

[12] Bull was part of the group with Bushell who were sent to Stalag Luft III in the province of Lower Silesia near the town of Sagan (now Żagań in Poland).

[16] When the tunnel was found to be a little short of the tree line he is credited as the man who quickly came up with the scheme to use a length of rope to signal when the German guards were clear and men should emerge from the trap door and run to the cover of the woods.

[17][18] Travelling in a group of four escapees with Rusty Kierath, Jerzy Mondschein and Willy Williams, their plan was to catch a train at a small station south of Sagan to Bober-Rohrsdorf near Hirschberg, close to the Czech frontier.

[28] Bull received the following awards: On 25 March 2012, the Czech Republic held a ceremony honouring these men and unveiling a plaque in their memory in the city of Most (formerly Brux) where they were murdered.