Well I also work for a large UK based regional and was on my way to the airport and got a call from crewing saying I might as well go back home and get back in bed. The crewing officer told me what the situation was and that I was being shown as being on standby but the chance of me being called was zero so enjoy a bonus day off.
For those that were on their way to report or had already reported it wouldn't be good practice to show them as off when they had already made their way. Also, first thing the situation is being updated regularly so nothing wrong in keeping the crews on standby should the situation change and all hands on deck needed.
Just enjoy the extra time at home....no need to moan about everything!
