Early discussions with the garage unearthed the fact that they had already identified the problem via computer diagnostics. It may well be that the previous problems had all been affected by this fault too, as had been suspected, but not proved. Anyway the Master Air Flow Meter is contaminated, the requisite replacement ordered and this should hopefully be the last chapter in this unfortunate saga! After this episode the word "car" is banned from usage!!
A magnificent Red Kite floating over the back garden (!) raised the spirits sufficiently for me to commence a little bit of forward planning in the hope of being mobile after the weekend.