As one of my companies is involved (sub, sub etc.) in this business of PFI-ing service training and other bits and pieces, I have had to become familiar with the desperately arcane maths behind the programme.
Ppruners might not realise that any PFI deal is subject to highly controversial discount rates, by which the MoD (and all HM Gov't departments who do PFI) basically use the figures to justify moving the debt off HMG balance sheets and shovelling it onto revenue accounts (which are not part of the Public Sector Borrowing Requirement). In the process, investment can be "encouraged" down various routes........
Government departments (using our money) are then hamstrung over many years by paying this off, using "current" money--which reduces still further the money available for front-line services.
End result--Gordon keeps within his targets, front-line delivery suffers over decades.
Knowing something of what has been going on re. the whole St.Athan/Cosford business and the calculations behind it, I would bet that the former expands and the latter will shortly be acquiring a shade of brown.
Public sector finances--a whirling hall of mirrors.