Long time coming. But. Finally problem cured. :) Been living with this wobble for a couple of months just gonna work an back. Then last weekend we went to Coast, up m1. First time in months been above 50mph , any way wobble not only still there but much worse , at 85 steering shaking about quarter of an inch side to side , dangerous . Decided enough was enough an took peters advice, 2 new tyres on front (£75 each "maxis" nothing special) .back on motorway , result problem much improved, but still a slight shake. Bit the bullet , dusted off the Barclay card, 2 tyres on back. HEY PRESTO. Smooth as silk (well diesel silk). Happy happy happy. Thanks Peter an trev. Given this some thought an the only thing I can think of that could have deformed all 4 Pirelli p-zeros is that before I bought the car in October last year it hadn't been moved for a long time and flat spots had appeared. I didn't go on a motorway for a couple of months after I picked it up so didn't realise there was a issue. Once again thanks guys