The Home Office has quietly privatised the spy planes used by MI5 to gather information on UK suspects.

Previously, three specially kitted-out planes known as Islanders were given the task of flying over the UK on surveillance missions.

The nature of their work is speculated to include scooping up mobile phone conversations and sending them to GCHQ for analysis.

However, according to investigation by Secret-bases.co.uk, which monitors aviation movements, the work has been given to fast-growing private aviation group 2Excel with three brand-new aircraft called the Piper PA-31 Navajo.

They continue to operate from RAF Northolt by 2Excel’s Scimitar business unit, according to the reports. Run by former RAF officers, 2Excel is also thought to run air surveillance flights for the military. Its directors did not respond to requests for comment.

There are no public tender documents for the work.

A government spokesman said: “We do not comment on matters of national security.”

2Excel’s turnover leapt by a fifth last year to £16.8 million. operating profits jumped 34% to £3 million.

