Originally Posted by
majoreyeswater
Anyway, my question is, I realise he costs 10% miles and doesn't attract that nice Mr Brown's APD, but how much in taxes / fees / bunce will the little sod cost in longhaul F?
Do a dummy booknig on ba.com to your destination - one adult & one child. It should show you the price for the child, broken down in the base fare and the add ons.
Make sure you're sitting down when you get the relevant page, and there are no flies buzzing around the room ...