Guys, many thanks for your replies, much appreciated.

Its been a couple of years since I've done RTWs and never booked with the online tool before but it takes ages to get replies from both BA and QR in Cairo...guess we all know why .

Anyway, been playing with the tool and something that amazes me is how much the taxes and fees depend on the choice of carrier. For example CAI-LHR-HEL with first leg on BA and the second on AY the taxes come up GBP161 (!) higher than if I choose BA for both legs. Same date, straight transit LHR-HEL flights 2 hours apart.

Similarly, for LAX-LHR-CAI both flights on BA comes up GBP190 higher than choosing AA for the LAX-LHR segment. Just unbelievable!