The 57-year-old Lillis had almost 17 years of experience as a player with spells at Huddersfield Town, Manchester City, Derby County and Aston Villa. His coaching career started at Macclesfield Town before a spell at Halifax Town. Lillis worked with Gregory at Derby County but he has done most of his coaching at Huddersfield Town, where he has served as coach, caretaker manager and academy manager. He also had a spell as assistant manager of Northern Ireland.