The RAF 1941 pilot notes call the aircraft "Beaufighter II", is there any significance to the addition of the "F" suffix in some designations ie "Beaufighter IIF".
They had a high attrition rate and I think underpowered compared to the Bristol engine versions, which may have led to the loss rate.
Reading through the ADF Serials site the Hercules powered version seems to have a high accident rate caused by engine failures on take off and brake failures.