Don’t work at west mids but I work in my TOC’s resourcing team
I’m guessing the reason for the shifts is because the role will also involve providing a degree of on-the-day/live support for frontline colleagues. Things like making sure everyone has booked on and working with the station team leaders to keep track of who isn’t in work (due to sickness etc) and whose turns need to be covered last minute. Also manning the phones so people can phone up and ask about leave, swapping shifts, etc.
The people in my team who work in station resources do both roster planning and on-the-day support, even though their job titles suggest that they just do planning. So they do work shifts (although I don’t think they do nights).
A rostering job having shift patterns doesn’t strike me as unusual, most roles in resourcing departments will be shift based (although not all will involve nights) as even though they may have job titles that suggest they just do planning, the actual job may involve providing a degree of operational/real time support.