Just to clear something up, is the G1265 that everyone keeps mentioning, the Celestion Heritage G12-65?
Yep- that's the one- though I recently lucked out and got 4 x G12-65's very cheaply second hand for £22.50 each (date codes say 1979
) via eBay- I've just wired 'em up tonight into my old 1969 Marshall 4x12 & lit the fuse on the Overtone and stood well back! Truth is I'm still replacing the ornaments that flew off the wall - Glorious!
Moral: Well worth scouting around second hand for originals - the new one's are around £68+P&P each...