Thanks to jumpseater, Pronto and Spiney Norman for their contributions to this thread.
I have now found the details that I was searching for.
The aircraft was indeed an RAF Heavy with Canadian crew, a Halifax BII (tail code BB326) attached to 1659 HCU (Heavy Conversion Unit) of No 6 (RCAF) Group.
1659 HCU was a training unit dedicated to the conversion of bomber crews on to the heavier 4 engine bombers. During the course of the war the unit was based at RAF Leeming and RAF Topcliffe, both in Yorkshire. At the time that the accident occurred the aircraft and crew were based at RAF Topcliffe where the unit remained until it was disbanded in September 1945.
The accident occurred shortly after takeoff from Halfpenny Green at 13.15 on the 12th November 1943. Clearly those farmhands had been lifting (harvesting) the sugar beet rather than hoeing it.
The aircraft carried a crew of eight at the time of the accident, of whom seven lost their lives. The tail gunner Pilot Officer T M Murdock (RCAF) was thrown clear of the wreckage and despite suffering serious injuries recovered and returned home to Canada.