Originally Posted by firstlight

As others have said, the regulations on duty of care have no time limit. However it's certainly easier to persuade BA if you are a frequent flyer with them.

One example, we were moved to another flight due to cancellation several months before our trip. We got the flight changed to one that was more convenient instead of cancelling, but then claimed duty of care expenses for a late checkout in the sum of several hundred pounds when we got home which BA paid without too much issue.