Genghis........
Not sure if you have access to A History of Royal Air Force WOODVALE published by Merseyside Aviation Society. There are a couple pages in there about the THUM Flight operations. Seem to recall Aeroplane did a Database feature on
PR 19s and The THUM Flight was covered in that.
It appears they lost two in fatal accidents, 04 May 52 PM549 stalled on approach to Woodvale, 04 March 54 PM562 forced landed at Pulverbatch, south of Shrewsbury.
Planemike