This downgrade is a humiliating blow for a Chancellor who has staked his reputation on the UK's triple A credit rating.
The fact that economic stagnation, rather than current borrowing levels, has caused this downgrade proves that demand-sapping austerity is ultimately self-defeating.
With plan A now completely in tatters the Chancellor has an opportunity to change course next month and start prioritising growth and jobs over pleasing ratings agencies.
The decision by the ratings agency Moody's to downgrade the UK's AAA credit rating, is unwelcome news for the Government.
Britain's loss of its triple-A credit rating is grim news for the Chancellor. But why does the marginal downgrading carry such a high price?
George Osborne had set great store by Britain's triple-A badge. But is the loss of the rating a loss of confidence in his policies?