The Shock absorbers actually last very well on all the Mini models, But if you know the Mini has had track day use, you need to look closer, personally i`d walk away from it there and then. But a clonking or knocking noise from the rear of the Mini is a fair indication the top shock absorber mount bushes are worn. This can actually happen to the front shock absorbers too, although its less common. Now a similar sounding knock noise heard from the front end could also be another component being the front anti roll bar links or “D” bushes. Neither of which is a big issue or very complicated or very expensive to repair.
Another check, when parked, slowly turn the steering wheel from one lock to the other lock and listen to any banging noise that is coming from the whole steering column, don’t worry about the buzzing from the electric motored power steering – this is quite normal.
This actually indicates that there`s a problem with the steering universal joint or uj, and there`s a fix that’s available under Mini warranty. If you`re out of warranty though, the lengthy labour intensive job will mean it will be expensive to sort. That`s why so many Mini owners learn to live with the noise, it’s not dangerous just very annoying and doesn`t normally get any worse.