Well thanks for the interest - by no replies yet.
Checking Wiki - it seems the Hercules didnt become operational until '39 (anybody know what month) and that was the Mk I.
Yet it seems plausible that a P.88a prototype could be ready mid '38, so do they put in the lower powered Perseus engine - similar diameter to the Hercules, or wait? If so - does it just serve as a flying demonstrator i.e. "it handles well if underpowered" or is a small order to start the production line until the more powerful Hercules comes along also plausible!??
Alternatively, the 'A' might have been delayed, while the 'B' gets the priority - Vultures were available earlier. But on its maiden flight - it crashes due to engine problems, then the Perseus option may just be for basic evaluation, and weapon testing (which would be important).
Any comments please.