One secret the airlines definitely don't want customers to know about is back-to-back ticketing. This can save you quite a lot of money, but you have to be well organised.

It works like this: Suppose you have to go to London on a Thursday, but you want to come back the same evening. The cheapest same-day fare, according to all the airlines you contact, is £200.

But why not buy two restricted return flights at £69 each, one starting in Dublin and one in London, totalling £138? True, you will have to pay two sets of airport taxes instead of one, but that still only adds an extra £16.40 to the bill.

The first return ticket leaves Dublin at 8 a.m. and returns at some future date, while the second leaves London at 8 p.m. and returns some other time.

Even if you throw away the return flight of each ticket, you have just saved £45. But if you are clever about it, you can get a "free' trip to London by arranging the return leg to London before the return flight to Dublin.

Anyone who needs a one-way ticket should also check out whether it might be cheaper to buy a return, and discard the second leg.