No I didn't. I'm starting to wonder whether it's the rear spacers as I have a vague recollection of one of them being a pain to seat correctly. Was about to take them off today when it started raining. I'll report back when checked.

Failing that, a full hunter alignment is next.

Spacers removed this morning. Went out for a test drive and struggled to get to 30!! Possible knackered turbo. Will resume this thread when car sorted. 

I recently had lost a screw on the under-tray and the only symptom was major vibration at 75-80 on the motorway. I thought it was balance at the time as had a recent tyre change, but was something really simple. Worth a check maybe.

Sorted mine. Took the wheels off and rotated them in relation with the hubs.

I think a tiny wheel imbalance and a tiny brake disc imbalance had combined to give the vibration. By turning the whes 2 studs on the hub the vibration has gone.