Clunk after braking on passenger side

[Rob_Quads]

My girlfriend has a 06 1.6L Mini. Around 3/4 months ago I replaced the front pads, there weren't any problems except having to replace the sensor which was a bit of a pain.

Just left week the car ran out of warranty and I started to hear a clunk at low speeds. We worked out that the clunk occured AFTER braking as long as you didn't stop i.e. your pulling up to lights, brake then release the brake and cruise to the line, after releasing the brake it clunks, comes from only the passenger side.
If you brake and come to a stop it does not occur

Any ideas what could cause this?

Cheers