Thanks to all. As Dave advised, I got my answer in TBB appendix C which notes that the rail of chairlifts can be ignored providing the chair can be parked clear of the stairs.
Kurnal, I provide a range of services, a lot within the leisure industry such as sports and social clubs. Whatever service I provide, I must ensure that it complies with the requirements of every statutory body. After 25 years of doing this, I have come to realise that some of the inspecting officers of these bodies almost relish the opportunity to tell you something is wrong after the job is done!
I remember heating pipes were directed up the side of a flight at low level and boxed in. The IO considered the stair width to be impeded and made me remove them at considerable expense. The situation with the chairlift is worse than the situation with the pipes. A strange beast, Regulations!