Hmmmmm. Time for an update. I haven't been around for a few days so popped into see the mechanic and he says now the engine is apart he has had a detailed look at it all.
Piston rings are worn but not too bad. He was expecting to find them mullered. Tolerances are well within what should be.
No damage to the pistons and rods.
Crank is ok. He has checked and apparantly a slight sideways movement is a design of the engine. no other movement can be made to it so big end shells, seals, etc are ok.
There is a deformation in one of the bores, not enough to see, but can be felt with fingers.
Top end is fine. valves, etc are in working order.
Breathers are not blocked.
No damage to block.
The pistons, rings, head gasket, etc are being sent off to an friendly engine refurb place for a second opinion. But he slightly puzzled. But as he said he would reather get it right first time than the car come back a week later still knackered. car doesn't smoke on start-up or idle. But give it a few revs and the rock concert somke machine returns. Smokes under power rather than on lift-off.
I trust the mechanic so we shall see in a couple of days what the probelm is. He's not an Alfa specialist but has been on the phone to engine refurb places and to an Alfa specialist he knows. They are all puzzled.
May well be expensive then!!!!!