NAO has assessed £ 7 bn of that to be already 'committed' as in:
"To date, the Department has not yet disposed of any of its 20 retired submarines, with nine of them still containing irradiated fuel. The Department plans to take a further three submarines out of service over the next decade."
- a little nibble of the other 3 bn was already taken out in this year about to close, for overruns with the first in class
Even if we would not need to touch the contingency again, the £ 7 bn somehow hangs together with the Gvmnt's latest estimate (a year old by now) that manufacturing the 4 Dreadnought submarines is likely to cost a total of £31 billion (including inflation over the lifetime of the programme); the Gvmnt have also set a contingency of £10 billion.
The 38 bn total magically equals the money we have decided to throw away (see below), so it is anybody's guess how much will be left for other defence procurement;
OBR, Table 4.22: Financial settlement components
UK participation in EU annual budgets,
plus Reste à liquider Other,
plus (longer) net liabilities
=Total 38.7 bn
almost all of which was going to (before delays with the 'start') fall due by 2028