In 1881, Forbes went to Brittany with fellow artist La Thangue. His time in France brought him into contact with the new plein air painters, which was to influence his style dramatically.
He arrived in Newlyn in 1884 and soon became a leading figure in the growing colony of artists. His national reputation was established with the acceptance of his ‘A Fish Sale on a Cornish Beach’ in 1885 at the Royal Academy, London (now owned by Plymouth City Art Gallery) and the purchase of The Health of the Bride in 1889 by Henry Tate, now at Tate Britain, London.
As the number of artists in Newlyn dwindled, Stanhope and his wife Elizabeth Forbes founded their School of Painting in 1899. This was to attract a whole new generation of artists to the area, including Ernest Procter and his future wife Doris Dod Shaw.
Throughout his life, Forbes was a familiar and popular figure in West Cornwall. Well into the 1930s, he was still often to be seen painting en plein air, surrounded by curious local children. He died in 1947, a few months short of his ninetieth birthday.