With almost enough copies of Fifty Shades of Grey to build its own sex dungeon, a branch of Oxfam in Swansea has asked people to stop donating the erotic novel or any of its sequels. “We appreciate all your donations, but less Fifty Shades and more 60s and 70s vinyl would be good,” wrote Phil Broadhurst, the shop’s manager, in a post on Facebook.

For a while, Oxfam published a list of its most-donated authors; between 2009 and 2012, Dan Brown was top. Could EL James and her Fifty Shades have beaten the Da Vinci Code author? “I think Dan Brown is still pipping it, actually, but [Fifty Shades] is up there,” says David Taylor at the Oxfam bookshop in Salisbury. Copies of Fifty Shades there are sent to the local depot for redistribution to other shops; his branch doesn’t sell it. “It sounds snobby, but there are 10 charity shops in our street and you can buy it in any one of them,” he says. “There’s no point in us selling it.”

Other bookshops are not reporting much in the way of bestselling soft porn. “We get our fair share,” says an employee at a British Heart Foundation shop in Edinburgh, but it isn’t one of the shop’s most-donated books. “I don’t even think we’ve got any in,” says the manager of a charity shop in Liverpool.

At the Red Cross bookshop in New Romney in Kent, only two or three copies of Fifty Shades have been donated. The most-donated books, says assistant manager Lorraine Logan, “would probably be Lee Child, Karin Slaughter, that type – crime fiction”. They also get a lot of military history and books about the area. “We’re in a quiet little town,” she says. I think she’s implying it’s perhaps not a hotbed of S&M enthusiasts. Quite what this says about Swansea I’ll leave to the imagination.