Dick wasn't a TP; he'd been lead Flight Engineer on the Princess before becoming Engineer i/c of testing of the SR53 and then later head of helicopter R&D on the Saunders Roe (nee Cierva) helicopters.
Not quite on topic, but there is a rather interesting book called "Backroom Boys" by Francis Spufford (ISBN 0-571-21496-7) . The first chapter covers the Black Knight / Black Arrow programme which was the UK's space programme (ha!) using Saunders Roe rocket technology - it doesn't go into much technical detail but might give you some leads, and is a good read.
G