Alex,
glad to hear that a new book about the 'Jav' is in the offing. I worked on them (Mk 7 and 9) on 33 at Middleton St George as an Air Radar Mech. It was an 'interesting' a/c for both aircrew and groundcrew ! As I recall we had cartridge starters for our a/c except for the T bird which was Avpin and a smaller 'banger'. Several instances of the system opening up the belly on start up as the banger exploded. And of the spare banger in the stowage going of when the a/c was taxyiing. 'Them was the days' !