Kelly, who has had previous spells in Yorkshire as assistant manager at Sheffield Wednesday and Leeds United – when Alan Irvine and Uwe Rosler were in charge respectively - is back in football after leaving Preston for personal health issues in August.

He was added to North End's staff earlier in the summer.

The 58-year-old previously worked with Richardson during his time in charge at Wigan Athletic.

AESSEAL New York Stadium, home of Rotherham United FC. Picture: PA

Kelly has a wealth of experience, having also previously worked at Blackburn Rovers, West Brom, Wolves, Nottingham Forest, Tranmere, Burton, Barrow, Malmö, Fortuna Düsseldorf and Fleetwood alongside at White Rose clubs Leeds and Wednesday – and Wigan.

Kelly’s contract will run until the summer of 2026 in South Yorkshire.

Kelly’s arrival bolsters the club’s coaching staff ahead of Saturday’s trip to Plymouth Argyle, where he will be joined in the technical area by current coaching staff Wayne Carlisle, Dan Green and Scott Brown.

Rotherham United add former Sheffield Wednesday and Leeds United assistant to their coaching staff