In theory there is an unallocated pot of several £bn to pay for priorities yet to be decided. So in theory again it would be a matter of Sentinel making it onto what I understand MoD calls its "whiteboard" of items it wants to pay for in that way. Of course things may not pan out like that, but the unallocated contingency is part of what appears to be an understanding established between MoD and Treasury as part of MoD putting in place better financial management. Whether the pot survives at all will be a good litmus test of whether a department can deal with the Treasury in good faith. I'm not betting the farm on that, but we'll find out soon enough.