Bicycle detail

I cycled to my dance class at St George's Church. There is a back alleyway round the side of the Church hall with a closed gate at the end leading to a small courtyard lined with high brick walls and the back entrance of the hall. I leaned my bike against the wall, so it was way out of street view as the gate was also closed. I have been leaving my bike there for a few years without a lock and it's always been fine, but when I came out an hour later it was gone.