A couple who bought an oil painting for less than £100 hope to make at least £100,000 when the Victorian work is sold at auction this weekend.

The bustling landscape of Salthouse Dock, Liverpool, has been in their ownership for 50 years since they bought it from a dealer in London’s Burlington Arcade.

The Leeds-born artist John Atkinson Grimshaw painted it in 1892 and it has hung on the wall of their Northumberland home, gaining hugely in value as his collectability increased.

It shows figures and carriages on the wide cobbled road of the dock where sailing ships are moored and atmospheric gas lamps shine on pavements and shops.

Grimshaw, who started his working life as a railway clerk before turning to art, became famous for such atmospheric canvases of industrial areas. The owners, who do not want to be identified, are in their 70s and never realised how valuable the piece had become.

Auctioneer Jim Railton, who will sell the picture at his saleroom in Alnwick, Northumberland, on Sunday, said it was rare that works of such quality and value were offered outside London.

He said: “They bought it in Burlington Arcade, from the dealer who is attributed with bringing Grimshaw’s works to the fore – and paid less than £100 for it. They knew it has gained in value over the years but did not realise it has the potential to reach such a record-making amount.

“When I saw it at their home I knew immediately it was a Grimshaw and one of his finest works. It is of significant interest to many collectors and to offer such an item for sale is a once-in-a-lifetime opportunity.”