Over the weekend, this image, first posted on Facebook, has been going viral on Twitter.
The spikes are located outside a residential building in Southwark and were apparently put up a few weeks ago. There's a nearby homeless shelter, but there doesn't appear to have been a particular problem with people sleeping in this doorway, according to residents.
The image has provoked a critical reaction (and some jokes).
An online petition to remove the spikes has been set up.
But there are a few things we should note.
First, while these spikes appear to have been recently installed, spikes in London are certainly not a new thing, as this 1994 Independent article shows. It describes the addition of spikes outside a branch of Barclays near Harrods, among others.
And there's a counter-argument regarding them. It's best expressed by a student nurse in London who'd rather remain anonymous: she uses the Twitter handle @NurseBlurg.
Rough sleeping is a complex issue – even when trying to gauge the extent of the problem.
And it's a varied picture across the country.
There's certainly no doubt that rough sleepers face a number of problems which require government intervention: not least a lack of affordable private housing for those on local housing allowance and the exploitation of a growing number of migrants by modern slavemasters.
There are two numbers you can call if you see a homeless person in need of help.
StreetLink is a new hotline which enables members of the public to connect with local advice and services. The London version of this service, set up in April 2011, led to nearly 2,000 calls being made to the helpline and 415 rough sleepers being helped off the streets and into accommodation in the first six months - a rate of success four times higher than traditional services.
It's now been launched nationally. The idea is simple: save the number (0300 500 0914) in your phone, and call it when you see a rough sleeper. You give the telephone worker a description of the person and their location. They will then get in touch with the council or a local homeless service to visit the person and provide support. If requested, StreetLink will give the person who made the call an update on what's happening 10 days later.
And as NurseBlurg writes: "If you see someone rough sleeping in London call No Second Night Out on 0870 3833333. They can get an outreach team to that person within 24 hours, who can start the battle of building trust and getting the person back indoors."