Hey Adey, i got some saddleman bags similar to martyns from the states. i surfed the net for days looking in the uk but gave up in the end. Try http://www.cruisercustomizing.com/
The good thing was the bags shipped in from germany, so i didnt get stung with import dutie.. .. Oh and ive got them on easy brackets..

Been there, Done that, Cant remember why! http://www.flickr.com/photos/12897423@N00/sets