A thief who had a change of heart returned five stolen paintings and left them behind a sofa.
Six paintings by local artists were stolen from the Thomas Storey Room at the Nice cafe in Lancaster.
But a week later, an anonymous caller rang to alert staff to the pictures behind the couch.
Police said one picture, titled Polluted Puddle Abbeystead, by local artist Fay Collins, is still outstanding and they are appealing for its return.
General manager at the Nice cafe Adrian Wilson said: “We hadn’t actually noticed the paintings going missing, its only when we saw gaps on the wall that we realised.
“The paintings were there one week and gone the next.
“We had a phone call one morning when a gentleman rang up and said one of his friends had taken the pictures and he had a guilt trip and left them by the chairs in the institute.
“The CCTV showed someone walking in with a bag and then out without one.
“It’s very unusual and a bit strange.
“Someone with problems decided to take them and then weren’t going to be able to sell them or realised they weren’t worth much. The landscape paintings were probably worth £200-£300 each.”
PC Peppi Agliolo said: “Artist Fay Collins is keen to get her painting back, which remains missing.
“I no longer have any more enquiries to make and have no idea who the thief or “good samaritan” is. Obviously we would like to speak to either person but I am more interested in getting the painting back and if it were to just turn up, I am sure that would be the end of the matter as far as the victim is concerned.
“The other alternative is for the person who is in possession of the painting can get in touch with the artist directly as their contact details are on a sticker on the reverse of the painting.”
The paintings were returned on November 1. Call police on 101 or Crimestoppers on 0800 555 111.