Spent a few hours in the right hand seat of one, during my approach radar course. During the practical phase we spent some time learning Surveillance Radar Approaches, using the Bournemouth ATC facilities (CAA/Nats were still providing ATC then). We were either practising the art of the SRA, off on a study period, or allocated to the CAAFU. I think there was/is a requirement for a competent observer to be present in the cockpit when practice instrument approaches were made. All this was in 1974, I'm not sure when this element of training ceased. The aircraft I remember was GANOV...in a museum now!