Mary's long and varied career started with seasons at the Edinburgh Lyceum, Glasgow Citizens, Newcastle Rep and the Liverpool Everyman.  In 1975 Mary co-founded Monstrous Regiment, the London-based feminist theatre company, performing and touring new work by writers such as Caryl Churchill, David Edgar, Bryony Lavery and Claire Luckham in the UK, Europe and the USA.

Credits include: Kate in Dancing at Lughnasa, Schiller's Mary Stuart, Emer in Heritage (Traverse); Mrs Mac in The People Next Door (Traverse Balkans Tour/East 59 Theatre New York); Pru in The House of Bernarda Alba (National Theatre); Father Lawrence in Queen Lear (Assembly). In 2019, Mrs Culfeathers in The Steamie at Glasgow Hydro.

Television/film credits include: Coronation Street; Still Game; Haggis; Crime 2; Insomnia Paramount; Connect; Unsaid; What Happens After Dark.