An adjustment device for a seat, the adjustment device permitting the seat to be adjusted along a motion path that provides adjustment of height and/or back inclination of the seat, the adjustment device comprising: two adjustment mechanisms, each adjustment mechanism comprising: a base part; a side part for attaching to the seat; a forward link mounted between the base part and the side part such that the forward link can rotate with respect to both the base part and the side part; a rear link mounted to the base part at a first position, the rear link mounted between the base part and the side part such that the rear link can rotate with respect to both the base part and the side part; an adjustment link attached to the rear link at a second position such that the adjustment link and rear link move in unison; and an adjustable strut mounted between the side part and the adjustment link such that the adjustable strut can rotate with respect to both the side part and the adjustment link, the adjustable strut being mounted to the adjustment link at a third position remote from the second position and mounted to the side part at a fourth position, the adjustable strut having a length running between the third position and the fourth position, the length being changeable between a minimum length and a maximum length to move the seat along the motion path by rotation of the forward and rear links with respect to the base part and side part; and a synchronisation mechanism connected to the adjustment mechanisms to coordinate movement of the two adjustment mechanisms along the motion path. two adjustment mechanisms, each adjustment mechanism comprising: a base part; a side part for attaching to the seat; a forward link mounted between the base part and the side part such that the forward link can rotate with respect to both the base part and the side part; a rear link mounted to the base part at a first position, the rear link mounted between the base part and the side part such that the rear link can rotate with respect to both the base part and the side part; an adjustment link attached to the rear link at a second position such that the adjustment link and rear link move in unison; and an adjustable strut mounted between the side part and the adjustment link such that the adjustable strut can rotate with respect to both the side part and the adjustment link, the adjustable strut being mounted to the adjustment link at a third position remote from the second position and mounted to the side part at a fourth position, the adjustable strut having a length running between the third position and the fourth position, the length being changeable between a minimum length and a maximum length to move the seat along the motion path by rotation of the forward and rear links with respect to the base part and side part; and a base part; a side part for attaching to the seat; a forward link mounted between the base part and the side part such that the forward link can rotate with respect to both the base part and the side part; a rear link mounted to the base part at a first position, the rear link mounted between the base part and the side part such that the rear link can rotate with respect to both the base part and the side part; an adjustment link attached to the rear link at a second position such that the adjustment link and rear link move in unison; and an adjustable strut mounted between the side part and the adjustment link such that the adjustable strut can rotate with respect to both the side part and the adjustment link, the adjustable strut being mounted to the adjustment link at a third position remote from the second position and mounted to the side part at a fourth position, the adjustable strut having a length running between the third position and the fourth position, the length being changeable between a minimum length and a maximum length to move the seat along the motion path by rotation of the forward and rear links with respect to the base part and side part; and a synchronisation mechanism connected to the adjustment mechanisms to coordinate movement of the two adjustment mechanisms along the motion path.