Ok ongoing update, what a complete pain of a job, thanks for the advice of pedal removal revealing 4 extra nuts, so 8 in total. 4 on the pedal box and 4 below the pedal box hidden. The booster is not glued in. Problem 2 now is that with all nuts off there is not enough space to withdraw the booster from the bulkhead, the 4 pins on the booster are about 65mm long and they are about 45mm of space without lowereing or disassembling the engine, which i will not do. I have resorted to removing the battery giving me side acces with a jigsaw, cutting off the bolts. I think the top 2 bolts have room to come out, its just the bottom 2, 1 of which is hidden. Im going to rotate the booster on its last pin and cut that too. Then im going to have to cut an inch off the bottom 2 booster pins on the new booster to allow re-assembly, I will tell you if it works ok!