I believe gifts over a certain are taxed ,it’s unearned income.I could be wrong but Stew himself could be taxed ,he’s not a registered charity and earning £20k basically
I reckon that would only be the case if it goes into his bank account, whereas if it’s through the Just Giving platform (or similar) and it goes directly to the nominated recipient, then I doubt it would be an issue.
And besides, people do this a lot for raising money for medical bills etc. and I’ve not heard of taxation on that before.