G E Treweek was born in Redruth in 1869, the son of a bank clerk and later, manager. At Redruth School of Art he gained a Teachers Certificate. He first exhibited with RCPS in 1886, in the Amateur section, but by 1888 was included in the Professional section, exhibiting regularly until 1895.

Around 1902 Treweek moved to Plymouth, working as a bank clerk. In 1918, aged 49, he married Winifred Hewer. The couple had two sons and the family subsequently moved to Stowmarket in Suffolk, where he held the position of head cashier at Barclays Bank. There he exhibited with Ipswich Arts Club, although his subjects were Devon and Cornish scenes.

After retiring from the bank in 1929, George and Winifred moved back to Cornwall, settling in Newquay. He became a member of STISA in 1936 and continued to exhibit there until 1954. Retirement offered the opportunity to devote himself to painting, and he became prolific in both watercolours and oils.

In 1957 he was widowed and living in Burnham, Bucks, near his son. Until shortly before his death in 1961, aged 92, he continued to paint Cornish seascapes.