Prior to that, however, on 12 June 1943 24 officers, escorted by two fake German guards, made another mass escape attempt, the "Delousing break", Welch and Flight Lieutenant Walter Morison among them.
This pair walked to a nearby airfield and attempted to steal a Junkers W 34 while wearing fake German uniforms.
The other 24 POWs were returned to camp, but Welch and Morison were sent to Oflag IV-C at Colditz.
While at Colditz he entered a competition, sponsored by the Royal Ocean Racing Club, for prisoners of war to design an offshore yacht of 32–35 ft waterline length.
Via the Red Cross, he submitted detailed drawings and calculations and won the first prize of £50.