how did this pass an m.o.t?

I can answer this for you, the wheel bearings are checked for ''play'' meaning from left to right or top to bottom, there can be a wheel bearing noise/grinding but have no free play in it, thus its going to pass its M-O-T simply because its road legal and NOT dangerous.
If its got play ''wheel movement'' apart from the obvious going round motion then it would fail its M-O-T.
Hope i have helped.

Kev
October 2008