The Ministry of Defence has inked a ten-year deal worth £1.5bn with HP, Fujitsu, Airbus and CGI for IT and comms.
The department estimates the mega contract will save £1bn over that period.
However, the MoD is not known for having the best track record in delivering cost-efficient IT programmes.
For example, the deliverability of its £7.3bn, 14-year defence IT programme due to be complete this year, was marked as "high risk" by the Major Projects Authority.
In 2013/14, the MoD spent £1.8bn on IT running costs, by far the largest slice of IT spend in government.
Defence Secretary Michael Fallon said of the latest contract: "We must keep pace with those who pose a threat to UK security, whether overt or cyber-based. The new contracts will enhance our fighting capability and make us more efficient in our work."
"Alongside this enhanced capability we have managed to secure huge savings of £1bn over ten years. All of this money will be reinvested back into defence, ultimately helping keep Britain safe."
The MoD is also shifting users to the cloud, and as we exclusively revealed some months back, has signed the largest Microsoft volume licensing agreement across the public sector, valued at £41m over three years.
In year one, the MoD will roll out Office 365 to 90,000 users, some 150,000 will move by the second and 180,000 by year three. The Atlas consortium will help roll out the service.®