In the 1976 10-lap Production race (two riders per bike) there were a number of H1s ridden.
Tom Christian / Dave Harrison - Manx - 40th
Roger Sutcliffe / Ronnie Russell - Manx - retired
Gerry Mateer / Joe Lindsay - Irish pairing - retired
Asa Moyce / Keith Buckley - UK pairing - retired
Phil Carpenter / Gordon Pantall - Welsh - retired
Pierre Soulas / Alain Terras - French - retired

It didn't cover itself in glory that year!

We have pictures of all these bikes within FoTTofinders