Strange knocking noise

[squeeam]

I've just noticed a knocking noise on my '03 Mini One when I apply the brakes. I've had new front brakes fitted about 6 months ago (non Mini garage) and rear ones fitted about a month later (Mini Garage). I did have new tyres fitted yesterday but I'm not sure it would be connected with that. It may be that this noise has been happening for a while but I've normally got the stereo blaring so I'm not totally sure how long it's been going on for.
Also, when I went out in my car today it wasn't happening until about 5 miles into my journey and then there it was again, car going along, apply the brakes and this one knock can be heard.
Can anyone help or advise please.
Regards
Squeeam

[CoNs]

i get this aswell.. but it when i have braked, and i am just about to stop, hear a slight clunk

[squeeam]

Now you mention it, it's more of a clunk than a knock. It's a bit like being at the doctors and trying to describe a pain.

[SeanCooperS]

I have the very same thing come to a stop and when i release the brake i get one loudish clunk from the rear of the car anyone any idea?