MediTek is a US-based stairlifts manufacturer with a strong UK presence. They sell both directly and via a network of dealers. Some of their marketing is directed towards health organizations, not individuals.
MediTek carries four models of stairlifts; the straight, the curved, the external, and something not much described in this segment, the 'stand & perch'. This latter stairlift does not have a full seat, but instead invites a sort of lean. One may suppose it may be appropriate for really narrow staircases, where space is an issue, or where the rider has trouble with genuflexion.