Happened to us a couple of years ago.
We dont normally work in London (we was literally begged though - and it was certainly made worth our while

), and didnt really fancy it for some reason, couldnt put our finger on it. Anyway, 2 toe rags on a bike broke our van window and nicked our laptop, printer and all associated paperwork. Worst of all we couldnt finish the job (obviously) and we refused to go back and finish it.
Can you claim on your insurance? We have a comprehensive policy that not only covers the basic liability/treatments risk but also stock, business equipment (machines & computers etc), and money/assault (if you get robbed with your takings!).
Kev