Thanks everyone for your suggestions, particularly tony-t, we too thought we had bought a "pup".
The car wasn't too bad on the initial drive but has become worse or we are just more aware of it. We thought there was
something seriously wrong with the car despite the £800 service, new bushes and MOT and assurances from the
BMW specialist garage. Anyway, thanks to your advice we have been looking at the tyres and there are two different kinds on the
front so will buy two new ones and see how it goes then. So thank you all for your suggestions.