A vehicle seat such as an aircraft seat 1 comprises a seat pan 2 and a backrest 3. The backrest 3 includes a movable element 16 which is detachable from the backrest and attachable to the seat pan 2 to extend the seat pan surface. The movable element 16 may for example comprise the cushion and supporting structure of the headrest part of the backrest or may comprise just the cushion. Thus, in a row of such seats, an extended bed-like surface may be provided without adding substantially to the weight or bulk of the seat.