Ruari has had a 12 year relationship with the Palace Theatre, starting with Alfie in 2005. He has subsequently designed; Copenhagen, Mrs Reynolds and the Ruffian, Family Business, Time of my Life, Our Brother David, Equally Divided, Love Me Do, and Poppy and George. He also designed co-productions of Tartuffe (ETT/Liverpool Theatres), Medea (Headlong), and Blue Remembered Hills (Northern Stage).

He has designed for almost all the regional theatres in the United Kingdom including; Birmingham Rep [Associate Artist], West Yorkshire Playhouse, Northern Stage, Bristol Old Vic, Nottingham Playhouse, Plymouth Theatre Royal, Liverpool Everyman and Playhouse, Derby Playhouse, Salisbury Playhouse, Theatr Clwyd.

Design credits include: Mappa Mundi, Frozen, The Waiting Room, The Red Balloon (National Theatre); Titus Andronicus (Royal Shakespeare Company);Othello [Trafalgar Studios]; The Solid Gold Cadillac (Garrick); A Busy Day (Lyric Theatre); Peggy Sue Got Married (Shaftsbury Theatre); The Snowman (Peacock Theatre) Toyer, Betty and Joan  (Arts); The Three Sisters on Hope Street, The Glass Room, Gone to L.A. (Hampstead Theatre); Henry IV parts I and II (Washington Shakespeare Company, USA); West Side Story, The Sound of Music (Stratford Festival, Canada); Hamlet (Birmingha and Elisnore, Denmark); Oleanna, Educating Rita, Pravda, The Critic, The Real Inspector Hound Chichester).

Opera credits include: Der Freischutz (Finnish National Opera); Peter Grimes, Cosi fan Tutte (Luzerner Opera); La Cenerentola, Il Barbiere di Siviglia (Garsington); L’Italiana in Algeri (Buxton); Les Pelerins de la Mecque, ZaZa (Wexford).

Ballet credits include: Bruise Blood (Shobana Jeyasingh Dance Company),  Landschaft und Erinnerung (Stuttgart Ballet, Germany); The Protecting Veil (Birmingham Royal Ballet), The Snowman (Seoul, London, Birmingham Rep, Tour).

Ruari has taught technical students at LAMDA, Bristol Old Vic Theatre School, Central School of Speech and Drama and RADA where he has also worked on the MA Directors course. He has teaches student theatre designers in costume and set design at Nottingham Trent University.