Ennis was born in 1933 and educated at Moseley and Birmingham Art Schools. He was apprenticed as a lithographic artist and then worked as an airbrush illustrator for a leading multi-national advertising agency.
He was elected as an Associate of the RBSA in 2011, and as a full Member in 2011.
He paints in watercolour, oils and acrylics and covers a wide range of subjects, including land and seascapes, French markets and café scenes. Artists who have influenced his work are Curtis and Hammond, and, from earlier times, Russell Flint and John Sell Cotman.
Apart from undertaking commissions, Ennis specialises as one of the few antique clock dial restorers in the country. This entails repainting the faded landscapes and flowers and gold leafing the various designs on longcase clocks from the eighteenth and nineteen centuries. Other interests include model boat building and photography.