The redevelopment of the Eastenders set has increased by £27m and will take an extra two-and-a-half years than originally planned, a report has highlighted.
The National Audit Office (NAO) has found that the BBC’s plans to build a new external set for long-running soap Eastenders “will not be able to deliver value for money” in the way it was first thought.
The body said that the BBC had “insufficient expertise in construction project management to identify critical issues”.
The E20 development was originally set to cost £59.7m in 2015 but had increased to £86.7m in the revised budget approved in May.
Construction had been delayed by an estimated 31 months and is now set to be completed by May 2023.
Development plans involve a temporary replacement set for the BBC to use while construction is under way on the new-build.
The replacement set alone is estimated to cost up to £54.7m, almost the full original budget for the whole build.
The NAO said that the temporary replacement was never formally discussed as an option in the original planning in 2013.
The auditing body said problems that caused delays and overspending could have been addressed earlier by the BBC.
It said critical design stages were completed without approval, causing over 70 subsequent design change requests at a further cost of £440,000.
The initial 1984 Eastenders set was constructed from wood and plaster and was only intended to be used for two years. Its degradation has now caused delays in the show’s production due to health and safety concerns for the cast and crew.
NAO head Amyas Morse said: “The BBC will not be able to deliver value for money on E20 in the way it originally envisaged.
“It is surprising that some of the reasons for this were built in from the beginning.
“Despite recent project management improvements, E20 is late and over-budget against its 2015 plans. We believe that the planned benefits are still broadly achievable, but given the high-risk nature of E20 it will need close scrutiny until it is finished.”
Other problems listed in the report included lack of communication between the construction team and the TV production team, higher than expected inflation, commercial challenges, and physical obstructions such as asbestos.
Last year the BBC appointed Wates as the contractor, but negotiations were delayed as the company sought clarity over design requirements before proposing costs. The corporation signed the front lot contract with Wates in September for £24.5m, some £9.5m more than they originally budgeted.
Meg Hillier, chair of parliament’s committee of public accounts, said: “It is concerning that the BBC has been unable to keep to budget and time on this project again, given my committee had already heard about the need to revise its scope in 2016.
“It is critical, given the BBC’s funding pressures, that every pound of licence fee payers’ money is spent effectively.”
A BBC spokesman said: “The set of Eastenders was built in 1984 and only intended for use for two years.
“Over 30 years later, the show remains one of the BBC’s flagship programmes and yet is filming from a set that is no longer fit for purpose. The new set will be suitable for HD filming for the first time and extend Walford to better reflect modern East End London.
“It’s a large, complex project, which has already delivered many other vital improvements at BBC Elstree Centre but like any building work of this scale there have been challenges on the way, including construction market issues beyond our control and from working on a brownfield site.
“As the NAO recognises we’ve already made improvements and are keeping the project under close scrutiny.”