The deputy leader of a London council has stepped down after total costs for the Marble Arch Mound doubled.
Westminster City Council’s original forecasts put the bill at £3.3million, but costs for the 25-metre man-made mountain have since rocketed to £6million.
The council says it has now launched an internal review into what went wrong with the project.
The day after opening to the public on 26 July, refunds were offered following what the council called “teething problems” with the attraction amid complaints it was still under construction.
The leader of the council, Rachel Robathan, said in a statement on Friday that her deputy Melvyn Caplan had resigned with immediate effect – calling the rise in costs “totally unacceptable”.
Ms Robathan said: “The Mound opened too early, and we apologise for that.
“It has become clear that costs have risen more than anticipated and that is totally unacceptable. Our original forecast cost was £3.3 million. Total costs are now £6m, covering every aspect of the project: construction, operation and eventual removal.
“With regret, I have accepted the resignation of my deputy leader, Melvyn Caplan, who led the Mound project. We have also instigated a thorough internal review to understand what went wrong and ensure it never happens again.”
The mound, built in the middle of one of the capital’s busiest tourist areas, was planned by Dutch architect company MVRDV and was designed to give views of Oxford Street, Hyde Park, Mayfair and Marylebone.
On Friday, the council announced that tickets for the mound would be free for August. It it due to be open until January 2022.
Prices to walk up the mound had ranged from £4.50 to £8 for adults.
Ms Robathan’s statement went on: “We are determined to continue our hard work to restore our city’s vibrancy, bring back visitors and ensure people can keep their jobs,” Ms Robathan said on Friday.
“Doing nothing was never an option. So when the Mound fully reopens in September, I hope that people will come and see it for themselves.
“The Mound may delight or divide views and that’s ok, but we’re confident that in the end it will fulfil its original brief – to get people back into the West End and remind them of why this is a world class City.”
Melvyn Caplan served as a councillor for Little Venice Ward from 1990. The Conservative was also a former leader of the council.