My sister has been invited to a 60th afternoons tea in a hall above a local pub. However the lady holding it has asked that everyone does a lateral flow test before they go
Should she insist that everyone does the test.
Are you asking that instead of 'asking' for folk to have the test, the host should 'insist' they take the test? If so, then yes. Her function, her rules.
Absolutely!
If I was one of her guests I’d be more than happy to do a test, in fact I’d be relieved that she insisted everyone does a test, a bit safer for everyone.
Here if you want to eat indoors without proof of vaccination you have to take your test equipment with you and do it at the door of the restaurant on weekends, because of people coming down from high risk areas
That’s what the tests are for; everybody ought to be getting a regular supply and using them. That said, she will have no way of proving that they have taken one. I know one lady who said she would rather catch Covid again then take a lateral flow test. And another friend is sick phobic, and refuses to take them. She can only ask.