Her paternal grandfather was the author and Punch cartoonist George du Maurier, who created the character of Svengali in the novel Trilby.

After her father's death in 1934, du Maurier, together with her mother and her elder sister Angela, moved from Cannon Hall, the family home in Hampstead, to a smaller house nearby.

In 1946, she left Ferryside for a studio in St Ives and held her first exhibition at the town's Society of Artists' autumn show.

In 1953, Welch and du Maurier moved together to Manaton, a village in Dartmoor, Devon where they remained for the rest of their lives.

She continued to paint all her life and exhibited her work in galleries in London and in Cornwall, with the St Ives Society of Arts as well as the Newlyn Artists.