Whilst I agree with the technical / legal responsibility as described by Anthony, Dave, myself and others in their responses I also recognise the practical scenarios that we often encounter carrying out risk assessment in a myriad of different buildings, with a whole range of different users and the appropriateness in some cases for individual PEEPs and in others for generic PEEPS. Multi occ office buildings are commonly encountered with no individual employer having persons requiring individual PEEPS but the occasional visitors to each employer or the risk of an individual employee falling ill and needing help in an emergency sometimes points to an evacuation chair being an appropriate risk control measure in the circumstances. We must all have seen it- 2 or 3'different types of chair in the staircase all provided by different employers, some having done nothing, and on asking questions you discover patchy training if any.
In such circumstances I have gone along with what Messy suggests and persuaded the Landlord, in their role to co-ordinate and communicate, to manage the evacuation of the communal areas, to provide equipment such as evacuation chairs and to liaise with employers to nominate fire wardens to use the equipment on behalf of all employers. I have had such arrangements working very successfully in many buildings over many years, but conversely have met point blank refusal from other Landlords. Good landlords will do it with minimum persuasion.