I'm seeing, increasingly, where LCCs have a hold, that some airlines are now allowing discount one-way tickets. Example of this are the 'near' short-hauls Ex-LHR from BA and BD.

This does have its downside, however. As a business traveller, how can I justify a fully flexible ticket, when I can buy a one-way to where I'm going for, say £30, and then the return leg for €50 when I know when I'm going to be travelling? Before, that kind of travel would have cost maybe £350 for the Y ticket.

It also leads to some slightly strange outcomes. Because airlines tend to charge less for tickets originating outside their 'home' market, and because of currency fluctuations, it can be cheaper to buy two one-ways than a return. I do this quite frequently on BD on LHR-AMS.