Monarch 720B and FL430
The Monarch 720Bs were my favourite and I certainly recall, again if my memory serves me, that going down to Tenerife at FL410, me on the jump seat, I forget why but think it was head wind the Capt asks for 430 and we "creep up" to that level, however Flt Engineer not happy and we go down again after only a short while . Lucky to have had a number of splendid trips with Monarch and Britannia at that time