Garrad convinced Lord Rootes' son Brian to quietly put up the $10k for his Tiger project without Brian's father's knowledge. Garrad contracted Miles to do a feasibility study, basically consisting of an engine swap with no set back. He contracted Shelby to do a total engineering package which included:
engine set back modified firewall/gearbox tunnel stiffened chassis spring rate changes rack and pinion steering large capacity radiator battery relocation to the trunk bunch of other smaller mods
The Mile's conversion took 5 days and cost $800. The Shelby version took 3 months and was the one presented to Rootes for approval.
Remember, I'm just passing along what I read, not necessarily agreeing with it.
Roland