Delays to the Foreign Office’s (FCO’s) Future Firecrest programme slashed about £15m from last year’s expected efficiency savings and added £36m million to costs.

The hold-up affected the planned upgrade of 11,000 desktops in 153 countries. Rollout will now start in the new year.

MPs are demanding advance warning about further delays, according to a committee report published last week.

Updated Cabinet Office security requirements are behind the revised timetable, FCO permanent secretary Sir Peter Ricketts told the committee. ‘The security authorities changed the rules on IT systems that could be connected to the internet,’ he said.