Originally Posted by vintagepilot

Some reasons for starting from somewhere other than UK given above - but mostly cost, and that more legs gives more tier points which is pertinent to the BA Exec Club.

But why specifically B2B, rather than separated flights - it is quick and easy, but it is also self-protected to a certain extent. If the B2B outbound is delayed, then by implication the return will be delayed and you will still make it. If you were to take an earlier flight out to your starting point, and that was delayed so much (or cancelled) that you missed the first flight of your main trip you would potentially be stuffed.