So after much faffing about, mostly because I rather liked my friends canon, I did the obvious thing and spent more than I was originally planning, and brought a Pentax.
Armed with a 16-50 f2.8, I started walking round London whilst waiting for a friend of mine. There was some commotion on London Bridge and I was able to snap this:
Starting to really like the lense, it was kind of the reason i went for the pentax, after spending a couple of hours playing with all sorts of combinations (and been told how i was using them wrong ) I settled on this combo, the quality of an inside low light shot at 400 iso is really quite amazing, and the anti shake and I seam to get along well.
I think i'll start trawling ebay, manual 50mm 1.4 with a K fitting can be found for < £50!