the "Golden Rule" (authors: G Brown and E Balls), which says that over the economic cycle UK will only borrow to invest (ie, no debt for provision of services in any one year)
Let's not forget it was Broon who b@st@rdised the word "investment" when he didn't want to say "spending increase", but how is the procurement of equipment for HM Forces not an investment worthy of state borrowing? Maybe HM should ask her PM?