Isobel Heath was born in Yorkshire, and studied under William Ritson, Robert Blatchford and at Colarossi's in Paris before going to Leonard FULLER's St Ives School of Painting  in the late 1930s. She first exhibited on Show Day in St Ives in 1940.

She was married for a time to Dr Marc Prati, the political correspondent to La Stampa of Turin, whom she met when he was a prisoner of war. By him she had a son. Isobel painted in watercolours and produced some large figure paintings in oils; she also made a number of pencil portraits.

During WWII she worked for the Ministry of Information, drawing and painting factory workers in the munitions and camouflage factories. It was also at this time that she completed a number of pencil portraits of American troops and local characters. According to Tovey, these wartime works are some of her best.

In Cornwall, Isobel lived at Bosun's Nest, Carthew, near Clodgy, St Ives. Resigning from STISA in 1949, she became a Founder member of the breakaway group, The Penwith Society of Artists. Isobel did not remain for long, resigning in 1950 due to the A,B,C group system which she declined to join - alongside Peter LANYON, Sven BERLIN and others. She rejoined STISA in 1957, exhibiting with them for the rest of her life.

Her studio was in Custom House Lane, St Ives but she often spent days out on the moors painting, staying overnight in her van. She published three books: Passing Thoughts (1971), Love (1973) and Reflections (1978). She died in St Ives.