Hi (again!) I've recently created a Google-group dedicated to the original Cambridge Audio HiFi.
formatting link
Currently there's the complete Cambridge Audio P50 Service Manual (80pp) - which covers all 3 types. There are also circuit diagrams / manuals / reviews for the Cambridge P50, also Cambridge T55 Tuner / Cambridge P60 / and Cambridge R50 speakers...+ info on others too.
Regards.
Frank