An L. S. Lowry painting which the artist sold in a bundle with another work for £10 because he was worried he had charged too much for it has been put up for auction with an estimate of £1m.
Going to the Mill was purchased by the Manchester Guardian's literary editor Arthur Wallace in 1926 for what would be about £520 in today's money.
The Stretford-born artist then sent Mr Wallace a note which read: "I think I've charged you too much. Can I give you another one as well?"
Simon Hucker, from the Lyon & Turnbull auction house in London, said the work was from a time when Lowry found his "unique voice" as an artist.
Going to the Mill was completed by Lowry in 1925, before he was widely known and 14 years before his first major exhibition in London.
He had, however, found some local fame, as after he exhibited work alongside two other artists in an architect's offices in Manchester in 1921, the Manchester Guardian's review stated he was someone who "may make a real contribution to art".
Going to the Mill was originally bought by Mr Wallace to be used to mark Manchester Civic Week, which celebrated the city's industrial success.
It has a price label of £30 on the back, but Lowry agreed to sell it for a third of that price.
