The Telegraph’s Alistair Sooke gives a pocket history of the Group of Seven in his review of the Dulwich Picture Gallery’s show on the Canadian artists:
Thomson only started painting in his thirties (he had little if any formal training as an artist). Yet in the years leading up to his death, a talent for capturing the great outdoors of his homeland emerged. Between 1912 and 1917, he painted around 300 oil sketches of the lakes and woods he encountered during expeditions into the Canadian wilderness. These vigorous works consist of dabs and jabs of vibrant pigment painted on to unprimed board so hurriedly that in places the wooden backing is still visible.
Thomson didn’t appear to value his sketches very highly (he gave many of them away to friends and admirers), but they transformed Canadian art.
Shortly after his death, galvanised by his pioneering efforts, a band of like-minded artist friends formed an alliance called the Group of Seven.
Painting Canada (Telegraph)