A person who spent the night in police cells after being arrested has donated their scratchcard winnings in the hope the force will buy some decent coffee.
A "thank you" card and £9 were mailed anonymously to Cambridge Police Station by the former "guest" on Thursday.
The detainee was critical of the quality of both the food and coffee during their stay and suggested officers serve better quality drinks.
Officers thanked them for the review and said the money would go to charity.
"Dear Police, the coffee and food was ****," the card said, with the writer then suggesting the force should try to source better quality coffee in future, putting the £9 winnings from two scratchcards towards that.
Officers added that they "take all feedback seriously and that includes the food and drink served in our cells", however, they hoped the complainant would not pay another visit to them anytime soon.
A spokeswoman for the force said they did not know who had sent the card and donation, as, "like all good restaurant critics, they have chosen to remain anonymous".
Asked about the brand of coffee served to detainees in the city centre cells, she said it would be "the best value for the taxpayer".