As somebody (thankfully) not having to deal with the UK education system, I do often wonder why parents in the UK tolerate such intrusion from schools into family life.
In my kid's school, the plays used to be during the school day. This was a problem for working parents, and feedback was provided to the school via the parent's council. As a result, a compromise was reached.
Those children in the first 2 years of school still have their concert during school hours. This was acceptable to parents as it was only for 2 years that this set-up would exist.
There are then 2 short concerts on 2 separate evenings. Those in their 3rd-5th years of school have a concert one night. Those in their 6th-8th years are the next night. The concerts are from 6-7.30, as this was most suitable for working parents and those with young children in their families.
Finally, before assigning any parts, parents are advised of the date of the concert, and asked to confirm if their children are able to attend. It is a simple yes/no. No excuses, no accounting for yourself. The parent decides what their family is doing that evening. If you can attend, great. If not, no problem.
I find it shocking that any parent would find themselves accounting for the whereabouts of their child to a teacher, and trying to work out a good reason for why their child was not in attendance at an event that was taking place outside of school hours, and that neither child not parent had been consulted with about partaking in. It is just not something that I think would be expected/tolerated here....