Q. I usually pre-book my seats to ensure I'm sitting where I want and not where they put me. However, on booking as usual this weekend for my British Airways flight in September (World Traveller Plus), I see that the usual fee for this service has increased from £33 to £37 if you wish to book an aisle seat. It's still £33 for the centre seats. I can see no reason to do this, but BA have you over a barrel if you want a choice of seats. What do you think? Pat Bone

A. British Airways has started differentiating between seats in the same aircraft cabin. As you discovered, in World Traveller Plus, you pay £30 for most seats – but £35 if you want to be next to the aisle. And in economy, the groups of three seats cost £30, but if you're happy to be in the middle four then it's just £26.

BA is perfectly entitled to set whatever fees it wishes for extras such as advance seat selection. Evidently, the option has proved popular with passengers, and it now being tweaked to extract a little more from travellers. To say, though, that the airline has you "over a barrel" is perhaps a little exaggerated. Many BA passengers decline to pay a penny more than they have to, and are content to wait until online check-in opens 24 hours before departure – at which point you can select any seat that remains in the cabin for no fee.

Families are in a stronger position; the airline looks at bookings involving children ahead of the 24-hour window, and undertakes to seat children with at least one parent. Experience suggests that most families are seated altogether without having to take any further action.

Even if you leave check-in until you get to the airport, and are unhappy with the seats that you are given, it is not too late. There is always a bit of last-minute shuffling at the gate. On board, many fellow passengers (except perhaps those who have paid for specific seats) are flexible in helping others who have particular requirements, and the cabin crew will do what they can, within reason, to meet your preferences.