After a 'deep & meaningful' with the service team I finally got a call from the techie working on the car. It turns out that a lot of what had been passed to me from the customer facing folks was complete rubbish.
The instruments do not lock out at the first sign of trouble, but the car's power management system will switch off unnecessary functions such as the clock and trip computer memories to save power.
The battery wasn't low, nor had the security system or GPS Safety Camera spotter caused an issue either. The security unit was faulty but has been replaced. There was an intermittent current drain of between 80-200mA, source unknown.
The issue appears to have been the instrument cluster PSU which was reset and now everything works fine. Whatever it was caused the instrument cluster to 'drop off' the data buses (as recorded by a number of modules) and refuse to power up. Power was getting to the unit though. The instrument cluster is one of the key data modules on the E70 and E71 - hence being over £1k to fix.
They've been trying to get it to fault again for over a week with no success. As the exact fault is unclear BMW GB won't spring for a new unit.
They are going to leave a copy of the fault log in the car for me so that in the event of a repeat occurrence there is a hard copy of the errors seen. The car logs 32 parameters from the last 40 drive cycles, but I don't have details of all of them. Suffice to say speed is one of them, others include temps, pressures, fuel system, rpm, gearbox operation, electrics etc etc.
Should get it back later today or tomorrow.......and I'll be able to drive again after next week (back to work on Weds after 5 months out).
