Thanks for that, guys. My wife has just reminded me that this happened once before whilst in Thailand and we used some "over the counter" drops, very similar to drops that I've previously used back in the UK - and to good effect! I'll be giving that a go first because if I can avoid doctors / hospitals and antibiotics etc then so much the better. Unfortunately, this is a common occurrence with a history of inner / middle ear infection and a mastoidectomy so it's highly unlikely that my travel insurance would cough up for any claim. If the drops don't fix it I will try St Mary's so thanks for the recommendation.