This advice may come unfortunately late for Stephen, but I can't emphasise enough how important it is to keep a record of your serial numbers. A simple spreadsheet or written list of them kept separately from the watches themselves may come in very handy if something as nasty as this happens - I add notes of any distinguishing features (marks on the dial, limited series issue numbers etc) to my spreadsheet. Having photographs of each watch could help too. Remember also that you never know if and when this could happen, so note the serial as soon as you receive a new watch, particularly as you will quite likely want to be wearing it a lot.

Stephen, I hope you weren't hurt in this incident and wish you luck in retrieving your watch.