Sorry but I must correct you, buzz boy! Yes, the B737-200s were on GB's AOC, but strictly speaking they weren't aircraft "from GB's operation". The aircraft concerned were operated by GB on its AOC on behalf of IAG - Independent Aviation Group - and it was IAG which had the contract with Easyjet.
So you actually have an example of aircraft being operated on behalf of a prospective airline (easyjet) by an existing AOC holder, but which were themselves already being operated by that airline on behalf of someone else!
The aircraft were acquired by IAG to operate IT flying on behalf of IAG's tour operator clients, and this they did in 1994 (and one unit still flew on IT in '95). But by autumn 1995 the aircraft were transfered by IAG to ACMI flying.