Have just noticed this thread.
I served my apprenticeship with Alvis and spent part of it at Baginton (Coventry) airport where 'Alvis Flight' was based in one of the hangars.
The Beaver was based there at that time and was owned by Alvis and modified for the Leonides in a bid to sell it to the MOD (Army), which obviously failed.
It was retained as a company aircraft and was flown by ? Williams the test pilot (apparently an ex-pathfinder Mosquito pilot) and JJ Parkes who was the Chairman.
Apparently he used it to fly his son, Mike Parkes, back to the UK after a race car crash on the continent.
It did not fly that much and was sold around 1972/3. Due to this the flight department closed and was re-invented as Alvair which operated for a few years as maintenance company