Not all GB3... callsigns are/have been repeaters. I was allocated one in 1975 - GB3UKP - when four of us (serving/former TA officers) operated from the summits of Ben Nevis, Scafell Pike and Snowdon in the same day - hence you can see the relevance of the callsign !! It took nearly a year to get the callsign as they had never had a 'special events' callsign operating from different locations let alone different countries in the same day! I can send a scan of the QSL if you'd like one.? Not sure if the feat has been repeated since? 8 stations spoke to us from all three summits and we got as far as London on a few watts of 2 metres!
I am here to ask a favour. I am currently G2SZ a legacy call sign from my uncle Cecil Goyder. This is the famous call sign. My uncle had another call sign (G)2+2 letters. If you have a very old call sign list from circa 1924 could you see if you can find his proper CS and I can arrange to give 2SZ to Mill Hill school where it properly resides.
Did you discover your uncle's alter ego?
Jack Hum's famous callboook lists a G.W. Goyder, London NW7 as 2HM
and this QST mentions G2SZ & G2HM as being the same person.
Back to Jack Hum's callbook and 2SZ is listed simply as "Wireless Society, London NW1"
Your uncle appears to have been a particularly celebrated radio amateur.
Write something about yourself. No need to be fancy, just an overview.