Crikey this brings back memories. Heron G-ANUO was indeed based at Leicester. If I recall it was registered to the General Electric Company before British Nuclear Fuels. It's Chief Pilot was Alan Firmin and that I won't forget - he had a terrific daughter - she was part of our social crowd then and lived in the same village; Kibworth. Being the family anorak, I was more interested in her dad's aeroplane and went for a test flight flip in it around the early seventies - it's even in my first logbook entered as 'passenger'. She is still a family friend to this day.
My Gran used to be a social pal of the Foxes. They also lived on our road in the village. I didn't realise they had a Heron too. They used to keep a very smart and sizeable catamaran in Poole Harbour, which us teenagers were invited aboard for a sail occasionally if we promised to behave. There was always a packet or three of Foxes Mints in the house.
Frank Lazenby was a garage owner - can't remember the brand though. There was also a guy who used to be at the flying club a great deal - he was one of the big knitwear company owners and drove a fabulous Red Ferrari 246 Dino - can't recall his name - my old lady would know.