There’s not an easy answer to this one. jmembery is right to point to HB regs Sch 1 para 1(g) as the one to consider, i.e whether the service is connected with the provision of adequate accomodation. But I don’t think we can ignore all particular needs of a tenant or set of tenants in determining this.
I suggest you have a good read of CIS 1460/1995 available from here:
http://www.rightsnet.org.uk/pdfs/cis/1460_95.pdf
It’s an Income Support decision, but it considers HB Regs Sch 1 para 1(g) in detail. In particular it says the following:
“Thus the question of connection with the provision of adequate accommodation under para 1(g) should not be confined to the character of the accommodation, but should take account of the personal needs of the residents….The question of what is the provision of adequate accommodation including how far the personal needs of residents should be taken into account, is a matter of fact for the adjudicating authority to determine in the circumstances of each case.”
So there is at least some justification for counting stairlifts and hoists (and for that matter anything not covered by paras (a) to (f) of Sch 1 para 1) as eligible.