Things on this thread are sorted out! The Quarter Bridge picture is from 1971 on practice. The first rider is number 21, Nev (maybe Ralph) Watts on a Honda CR93.
The second rider on a 125 Maico with number 38 is Jean Louis Pasquier. (So my first guess about a Maico was correct! Wrong rider though...)

The second picture on the thread is from Creg-ny-Baa 1970. It is Jim Curry with number 5 on a Honda, probably CR93.
All this is according to the official programs and result lists from that time. They are found now! Coming back to the other thread "Three more TT mystery photos... can you help? " later.