Am staff allowed someone else present a this meeting?

[HamandCheeseSandwich]

Staff are being called individually into a very senior boss' office, and being asked about their current job (duties, hours of work etc) this will all be written down and is part of a possible redundancy process.

Are they entitled to have someone there as 'witness'?

In short, no, IMO.

There are few occasions when you have the right to be accompanied, disciplinary and capability investigations/hearings being the main ones.

If redundancies do arise and they hold formal "consultation" meetings, you have the right to be accompanied.