Apologies if this has been covered before.
Airlines rotinely cancel the return leg if, the outbound leg has not been flown.
So: would it be wiser to buy 2 single legs to protect ones' investment OR are these legs fused together to constitute a return ticket?
People, this week nervous of being caught out by the fog debacle, could have resorted to the certainty of Eurostar trains in addition to their previously booked flights. In this case good luck would be if their flight to CDG or BRU were cancelled. Bad luck would be if BA did fly, and the return flight was invalidated.