Flint’s work is represented in many public collections including the art galleries of Aberdeen, Belfast, Birmingham, Brisbane, Brooklyn, Chicago, Dundee, Edinburgh, Glasgow, Indianapolis, Johannesburg, Liverpool (Walker Art Gallery), London (Victoria and Albert Museum), Manchester (Whitworth Art Gallery), Ottawa, Perth, Santa Barbara, Sydney, and Toronto.

Originally an illustrator he began to explore oil painting  and after displaying just three 3 oils at the Royal Academy he was elected an associate member. He was elected a full member in 1933.

The war interrupted Flint’s career (he was a Captain in the RAF)  and in his autobiography he wrote: “On getting out of uniform in February 1919 I found that so many people wanted my watercolours that I ceased to be an illustrator and became a painter”

In recent years, his prints alone have fetched several thousand pounds at auction and his watercolours have sold for between £20,000 and £99,000.