As ever, it is usually best to read the evidence transcripts before believing the hype.
Oral evidence - Defence Equipment Plan 2017-27 - 14 Mar 2018
While it is clear that PUS, DFin and DCDS(Cap) are all unhappy with the level of financial risk being carried, when one actually reads the evidence it is clear that figures of £20bn (over a ten year programme) are at eth extremes of credibility. There's also an illuminating discourse on both T31 and the Forex risk provision.
It is difficult to read the PAC report (and the associated media headlines) and identify how they relate to the actual evidence presented.....
And on the article on Prelude - don't forget that one of the highlights (often overlooked - and not really covered in the actual govt policy) in John Parkers National Shipbuilding report was that unlike commercial organisations who allocate control of long term strategic budgets to projects, the Treasury does not give MoD the same privilege. I know people who've been on that project in various forms since 2007 or so.