Born in Calgary, Alberta, Shelley trained at RADA in London, and worked for many years in the UK. She played roles in London's West End and at the Royal National Theatre, as well as leading roles in regional theatres. She was a regular in BBC radio drama during her time in Britain, and recorded dozens of audio books – titles including work by Margaret Atwood and Jane Smiley. She played “Rita King” for the first six series of the Children's ITV comedy series, Mike and Angelo, and made guest appearances on Drop the Dead Donkey, EastEnders and Chelworth
She also played the role of Sarah's stepmother Irene Williams in Jim Henson's 1986 fantasy epic Labyrinth. She has appeared in all seasons of Trailer Park Boys, both specials, and the feature film.