BORIS Johnson's VIP plane makeover is to cost almost £1m, it has been revealed.

A Downing Street spokesman has confirmed that the repainting of the RAF Voyager will cost £900,000.

The plane, which was commissioned by David Cameron for £10m, is undergoing a Union Jack-inspired red white and blue paint job at a hangar run by Marshall Aerospace near Cambridge.

At the time it was commissioned, it was intended for civilian and military use as the cost of the aircraft sparked public outrage, however the development that it will be upgraded with “national branding” has drawn suggestion that it will be reserved for official travel.

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One commentator and former RAF pilot described the plan as “project creep” and said: “It’s starting to look – operationally and politically – much more like Air Force One for Boris.”

A Downing Street spokesman said the plane “used by the Royal family and the Prime Minister is currently in Cambridgeshire for pre-planned repainting.” adding: “This will mean that the plane can better represent the UK around the world with national branding similar to many other planes, while also retaining its military refuelling capability.”

He explained that it would “promote the UK around the world without compromising the plane's vital military role” and explained: “At every stage we work to ensure value for money for the UK, and all of the work has been undertaken in the UK directly benefiting British suppliers.”

The makeover, which Ian Blackford MP described as a “vanity project” during Prime Minister's Questions today, comes two years after Mr Johnson complained about the aircraft's current grey colour, and said it was not always available.

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When he was the Foreign Secretary, he said: “What I will say about the Voyager, I think it’s great, but it seems to be very difficult to get hold of...And also, why does it have to be grey?”

The aircraft has a first class cabin for the Prime Minister, or the leading VIP on board, followed by club class for delegates and economy class seating at the back which is used mainly by the media travelling to report on foreign trips.