Thanks, guys. Went in to check today and no break-ins or anything, so all ok. I think it helped that a) at the Saturday service I told the whole congregation about the Friday thefts (pointed no fingers) and told them to watch their possessions. The (alleged) thieves stayed for about 15 minutes, which was intimidating but I guess they knew there'd be no pickings.
Then b) we have an Ethiopian church meets in our building, and they had a service from 8pm to 5am, with about 600 in attendance and a lot of police attention to keep them safe. Maybe the (alleged) thieves saw it wasn't the easy target they'd expected.That's what I told myself when the Ethiopian drumming was still going on under my window at 4am, anyway.
Tomorrow, which is actually today, is going to be a seriously OP day.