Possibly there's no partnership, but I'd incline towards feeling that there is. This may help:
http://www.hmrc.gov.uk/MANUALS/bimmanual/BIM72005.htm
You write
which the bank would not do if they were not in a partnership.
and possibly mean which the bank would not do if the bank did not have documentary evidence that they were in a partnership - this evidence which would make joint and several liability easy to prove in court.
If all properties were developed with the same people, then the same partnership would have done the work and a single trade would exist.
Yes, some of the current admin expenses may be pre-trading expenditure. The problem appears to be the range of partnerships he uses. Particularly when it comes to the tax nothings for abortive expenditure.