I heard the guy who runs Latitude, Reading and Leeds festivals on Radio 4 this morning. Asked specifically about whether he'll put up signs to advise people to wear masks inside tented stages, his view was that every festival needs to consider its age profile and that, since his festivals are mainly under 30's, he didn't think it was necessary because of their very low risk profile. I'd imagine EOTR has a broader age profile than this, especially as it's held after the schools go back.