I thought he wasn’t even in the UK to be arrested. Did he go back?

Edit:

Brand has not been placed under arrest, the Met tells NPR. The agency says he was interviewed and then charged via “postal requisition” — a court summons informing him of the charges.

https://www.npr.org/2025/04/04/g-s1-58260/russell-brand-rape-assault

I guess the OP thinks he got arrested by mail since that’s not even the article title.