On a school trip to Midland Radar at RAF North Luffenham, I was allowed to have a go on the 'height-finder'. I managed to get the 'level' of a Vulcan over The Wash. I think the kit used a device called a 'resolver' to obtain the aircraft's height. Had a look at the big radar too, (Type 82 maybe?). That was in '68/'69. Fuelled an interest in ATC. Result, I ended up talking to Midland as a Temporary CSC many years later. Nice folks, Midland, - always helpful. Anyone remember when they finally closed?