Had a very stressful 15 hours.
Last night I came home with dinner with friends and when I came back to the apartment I am staying in the key broke off in the lock and I couldn't get in.
Fortunately the people who own the apartment also have a guest house. I called the emergency number for the guest house and someone met me there. They put me up in one of their rooms and called a locksmith in the morning.
It was a very stressful night and I didn't sleep well. The locksmith didn't come until late morning and most of my day was wasted and couldn't go to Cambridge as I wanted to.