Born in Glasgow in 1950, Forrest attended Glasgow School of Art between 1969 and 1973 prior to becoming a tutor there for seven years. In 1985, he gave up his teaching so that he could devote his time to painting.

Forrest was elected a Member of the Royal Glasgow Institute of the Fine Arts in 1988 and has been a regular exhibitor there and at the Royal Scottish Academy since 1975. He has won numerous awards for both his painting and sculpture.

Examples of his work can be found in private and corporate collections worldwide. Notable collections Include: Argyll Group plc,Beatson Oncology Centre, BBC, Biocon (Bangalore India), Deloitte, Glasgow Art Club, Glasgow Museums and Art Galleries, Glasgow Royal Infirmary, ICAP plc, Lightbody Ventures, Macfarlane Group (Clansman) PLC, Maclay, Murray and Spens, MacRoberts Partnership, Mar Hall Hotel, National Museums of Scotland, New Edinburgh Ltd, NHS Greater Glasgow and Clyde, One Devonshire Gardens, Restaurant Andrew Fairlie, Gleneagles, Royal College of Physicians, Royal Scottish Academy of Music and Drama, Scottish Amicable, Scottish National Portrait Gallery, Scottish Opera, Stirling University, The Alexander Gibson Opera School, The Earl of Wemyss and March, The Fleming Collection, The Glasgow Academy, The Royal Bank of Scotland, The Royal Conservatoire of Scotland, The Shurniak Gallery (Saskatchewan), The Savoy Group, Whyte & Mackay, William Teacher & Sons Ltd.