Update

 What's been happening since the Q started behaving? Not a HUGE amount, I drove it up & down the drive, which told me the performance has improved (more than double the horsepower) but also that the exhaust catches on the drive where there's a small step from tarmac to slabs, so the car went up in the air on ramps & stands & between my brother & me we cut & re-shaped the exhaust primarily to go around the gear change which alows the exhaust to move up. Nothing is simple & moving the exhaust up made it clash with fuel pipes & the fat battery wires heading to the front. So I spent a day re-routing hoses & wires & I'm now just waiting on a rubber mount to hold the centre section up & it's pretty much drivable. I need to contact a man to have it mapped next, but when I get back fro the Rogue Runner's Scotland road trip, this yea entitles "The Return of The Masked Pensionistas", I'll get that bit sorted & then it's road-worthy.