When I lived up country, about 20 years ago, my van was broken into on 3 occasions over about 4 years. By pure luck, on each occasion I was working on a full refurb and most of my tools were left onsite which was reasonably secure so losses from the van were minimal, 100 quid tops. Conversely, a mate parked in B & Q for 15 minutes and his van was emptied, maybe £5k worth of kit, that was by travellers who targeted the area for about a week.
When I moved to Cornwall it wasn't something I worried about (although it did happen to a much much smaller extent). Retired now so not a concern but my heart goes out to anyone who is a victim of tool theft, it is a horrible crime and the affects on the victim are more far reaching than the financial loss.