I did a bit more work on the under dash trays and the multitude of wiring in this area. The ECU is mounted and I've cut the holes for and fitted the heater vents which direct hot air to the footwell. This all took a lot longer than I'd planned as I had to try several different positions in order to gain enough clearance behind the dash for the back of the instruments. I think I've got it sorted now and can begin to permanently fix the Mast wiring loom and the additional wiring I've put in for heated seats, 12v power outlet, neutral safety switch etc.
Another trial fit of the dash and somewhere to put it out of harms way. I couldn't finish the wiring for the dash loom and the modifications I'd made as I'd run out of a few bits and pieces and being bank holiday, it will be a few days before I can get them. Fingers crossed, the big switch on will be next weekend.