The UK Government's Department for International Development is renowned in Whitehall for not having the sharpest pencils in the box from the pool of civil servants, among other things they started this St Helena project by asking UK construction contractors to quote Fixed Price for the project without even giving the facility for those tendering to visit the project site and do a detailed engineering assessment. Among other things there's still a grudge in Whitehall against the construction contractors who built the Falklands airfield, a not dissimilar challenge, in the 1980s, and are felt to have "made a fortune".
One result is they seem to have inadequate budgetary provisions for all the variations and rework at the end of the project. It's generally true that if you go for the cheapest contractor, rather than mainstream ones you give continuing projects to, they will be looking for every little variation to be priced and confirmed before they start. Correcting design errors and identifying who will pay for this can start to really drag the project conclusion.
Top blunt pencil is the Secretary, Justine Greening, MP for Putney, who in an ill-starred brief stay heading the Department for Transport (until she was finally sussed by Cameron and moved to the dead water of the DfID) was renowned for being no friend of aviation, or anything to do with it, mainly on the basis that her millionaire neighbours on West Hill don't care for hearing inbounds to Heathrow passing by their Sunday morning cocktail parties. I suspect that Saints have a slightly different approach to life.