Every time I tried locking it last night the alarm went off after a few minutes, even just using the key in the lock. In the end, I had to leave it unlocked, but luckily I have a couple of wheel clamps which fit and I can lock a bollard at the front of my drive, so it was impossible to steal without waking my neighbors up again. From what I've read on other forums, the bonnet sensor button can sometimes fail and that often sets off the alarm, so that will be the first thing I replace when troubleshooting.