The cost of redeveloping Gunnersbury Park has almost doubled to £39m, it has emerged.

It had been predicted that the cost of restoring the deteriorating park, managed by Hounslow and Ealing councils, would cost £20m at a previous meeting of the Gunnersbury Park Regeneration Board.

However, at a meeting last week, the council’s financial consultants revealed if the park was restored in line with their favoured proposal, a figure of £39m would have to be secured.

Paul Jardin, from Jura Consultants, said he believed £6.5m could be funded by English Heritage and the Heritage Lottery Fund and a further £2m from the two councils. It is hoped the London Development Agency would also contribute.

However, he stressed the remainder of the money would have to come from the development of houses in the park, which could result in the loss of 5.6 acres of the 186-acre park along Lionel Road North.

He said: “Our preference is restoring and upgrading, which we believe could be funded. This clearly requires securing funds from sources where we would be competing for funds, eg Heritage Lottery Fund and English Heritage but we consider that a strong case could be made.

“The enabling development [selling of land for housing] plus the councils’ own contributions would be required to complete the funding package.”

The favoured proposal would see the large mansion house used as a restaurant and for functions and conferences at a cost of almost £8m.

Gunnersbury Park Museum would be moved into the small mansion with the museum’s stored collection being housed in the stables. The conservatory would become a tea room while the historic landscape of the park would also be restored.

The regeneration board was offered three further options including a “mixed use” which would see more commercial use at the park, however it was reported that neither English Heritage or the Heritage Lottery Fund would be inclined to fund this.

An upgrading option, predicted to cost £49m, was seen as too expensive while the third option of doing nothing still had significant costs attached to it.

A questionnaire on the options is now being prepared by the board as part of a public consultation.

However, the plan to build on the land has already been met with contention after earlier proposals to build a small number of luxury houses was quickly played down by both councils.

A petition was launched by Ann Keen, MP for Brentford and Isleworth, which was signed by almost 2,000 people.

She said: "I have to question whether the money the financial consultants believe can be raised by selling off four-and-a-half acres will be readily available in the current economic climate.

“This needs to be seriously considered, because no one wants a perpetual building site - let alone 60 new luxury homes - in Lionel Road."