I never disconnected the positive - it was resting unconnected for weeks anyway so the caps and so on would have depleted charge without me connected the leads.
So anyway I just bit the bullet, some strange undefined behaviour at first and no response to the fob but then the alarm LED turned on and indicated it was immobilised but not alarmed, so I just went with it and turned it over with success. Took it for a 20min spin and now it appears to work with the fob alarm signals...
Just like the manual said - who woulda thunk
Out of interest, did I perhaps not read something that meant I should be aware that this is a North American forum only? (not saying you're excluding us Puma owners on purpose... I understand why they are a rare model in your parts)