Mike, Replacement PAR (RPAR) has now replaced the old CR62 system at all of the UK's military bases. The problem of it locking on to other aircraft passing through its "beam" has been resolved. It now "locks" the a/c on approach and provides the controller with a similar, although digital, display to the old system. I believe it's less user friendly though due to the lack of the old style primary return trails...
It's certainly not as easy to calibrate!