Note that those really low ex-Europe fares are only valid in a very specific two week window, either side of the easter weekend (Euro school holidays).

Interestingly, this doesn't match up with the UK school holidays this year so I suspect it gives BA a bit of a headache.

There are however some very aggressive prices out there - AMS-LON-HKG for £1370 where it's around £5k to take the same flights starting in London.

That HNL route can be augmented by flying BRU-HEL-LHR at the start, too!