While current tenants of the Clapham property are keen to mention that the room is fully furnished, both the words "room" and "bed" could be argued to stretch the truth: in fact the desres Alex Lomax was shown comprises a single mattress stuffed into a cupboard under the stairs.
Lomax's post on Twitter, comparing the room to Harry Potter's infamous dwelling while living with his cruel aunt and uncle in Privet Drive, has been retweeted more 2,400 times so far.
The asking price for the box-room stands at £500 per month excluding bills.
Advertising the property on london2let.com, the advertisers said: "We are looking for a friendly, open-minded and outgoing person to join our houseshare in a great period house in Clapham.
"We’re a good bunch and like to chill out a lot together – not really looking for somebody that just wants to stay in their room."
Yeah, no kidding.