Originally Posted by number_6
Harare. Presuming you don't care about cost of getting there. Actually several African countries have the same pricing (unfortunately it is in USD so no currency arbitrage play).
Sorry should have explained that I do not want to start at a point any further from London than Cairo. Thought I saw that someone was suggesting cheaper in Germany or France. I have LHR/CAI in A class left over from previous RTW. On next trip have two friends travelling with me who do not have LHr/CAi ticket so if there is a cheaper starting point that is closer to London than Cairo will take it.