Easyjet seem to indicate you can do this as long as you pay for a full fare seat. But how do you secure a group 1 seat that's meant for a 3 point safety belt with an airline lap belt?
If you've taken a carseat on the plane was it worth it, how did it work and which airline - ryanair don't allow it, or to book an extra seat for an infant even if you pay full price - I don't understand??