A troubled £285.5 million airport project financed by public money has "unquestionably failed" the British taxpayer and the residents of the remote island it was meant to serve, a damning report by MPs has said.
Commercial aircraft have been unable to use the new airport on the South Atlantic territory of St Helena because of the dangerous wind conditions, with the MPs on the influential Public Accounts Committee (PAC) saying it was "staggering" that ministers and officials did not foresee the problem.
The PAC demanded answers from the Department for International Development (DfID) about who was responsible for the fiasco and how much it would end up costing taxpayers.
Government lawyers are now understood to be examining some of the decisions taken during the course of the project.
International Development Secretary Priti Patel has vowed to ensure that lessons will be learned, DfID said.
The UK overseas territory could only be reached by sea and the new airport was meant to improve accessibility and boost tourism, with the intention of making the island self-sufficient.
The airport was meant to start operating in May 2016 but test flights a month before revealed the problems with "wind shear".
While the airport has since handled a small number of flights the wind conditions have prevented the operation of the planned commercial service.
The PAC report said: "The Department for International Development has spent £285.5 million of taxpayers' money on building an airport in St Helena that is not usable by commercial airlines.
"It is staggering that the department did not foresee and address the impact of difficult wind conditions on landing commercial aircraft safely.
"The department was evasive on the question of who should be held responsible, and is yet to hold anyone to account, either internally or externally for the failure to identify this fundamental issue. Nor has it identified the extent or cost of remedial action required.
"There is also doubt over whether the airport, when operational, will lead to St Helena becoming financially self-sufficient, due to significant uncertainties over projected tourist growth figures and a lack of progress toward attracting investment. "
"Thus far, the department has unquestionably failed the residents of St Helena and the British taxpayer."
The problem of wind shear on St Helena was noted by Charles Darwin on his voyage on the Beagle in 1836 and the MPs challenged DfID about why it had commissioned an airport paid for by the British taxpayer, without properly appreciating the danger of this effect.
Officials told the MPs that it had commissioned a feasibility study from engineering consultancy Atkins for the airport build and acted upon its recommendations, as well as taking advice from the Met Office and aviation regulators.
But the report noted that Atkins expressed doubts about local weather conditions, including the amount of turbulence that could be expected on approaches and recommended test flights before the runway design was finalised.
The report said a single test flight using a propeller aircraft was carried out, but the contract for the commercial service was to use a Boeing 737 - a twin-engined jet.
The PAC's Labour chairwoman Meg Hillier said: "The Government has an obligation to support St Helena but a £285 million white elephant serves neither its people nor the taxpayers footing the bill.
"The failure to undertake robust due diligence on this project is truly appalling. I also have serious concerns about the airport's business case, which was marginal at best.
"A more modest airport could have addressed the practical needs of the Saints. Scaling up the project may have made sense were it not done on the back of such unconvincing projections.
"The result is a disaster: a commercial airport that is not fit for purpose, no credible plan to salvage value for money, and no clarity on exactly who is responsible for the whole sorry mess."
A DfID spokesman said: "One of the first things the Secretary of State did this summer was to take concrete actions to get the airport up and running and to ensure the lessons from this project are learnt. We are already seeing the results.
"An external expert was brought in to review evidence of DfID's actions while an independent panel has been tasked with finding a solution to challenges presented by wind shear."
So far 18 flights have successfully landed at the airport, including three medical flights, and the St Helena government has released a tender for air services for a three-year period.