Following earlier reports that London’s Metropolitan Police will still have over 99% of its computers running Windows XP past the April 8 end-of-support deadline, the police force has told CBR that it has negotiated a custom support agreement (CSA) with Microsoft.

Responding to a request for comment, the Met said: "The MPS have a Microsoft Custom Support Agreement (CSA) in place for Windows XP, that will continue to support the MPS Environment.

"This will provide the support required to allow the deployment of the Next Generation Desktop on the MPS Estate which will ensure reduced risk as we exit XP from our estate."

A freedom of information request obtained by CBR revealed that out of 34,436 desktop PCs currently in use by the force, 34,210 of those are still running on Windows XP.

93.9% of its laptops will also still be running on Windows XP past the Microsoft deadline, with 2,307 out of 2,458 laptops on Windows XP.

On April 8, official security support for Windows XP will cease, where the operating system will become vulnerable to hacking and malware.

Microsoft has said it will charge up to £120 per PC to keep security support in place, with this cost rising to £240 in the second year and then £490 in the third year of support.

Using these figures, a standard support agreement will cost the force over £4m to keep its machines secure until April 8, 2015, with a cumulative cost of £31.9m if the Met want to keep its machines secure until April 2017.

However, it is likely the custom support agreement will be less than this. CBR will update its readers on any new pricing details for the agreement as soon as they become available.