In the last week of July, executives at Blackstone and KKR were rocked by a new and unsettling experience. As the private equity groups entered the second round of bidding for yet another huge leveraged buy-out – the $16bn (£8bn, €12bn) purchase of Cadbury Schweppes’ US drinks business – the deal kept getting more expensive.

What was happening? Each time the buy-out funds checked in with Morgan Stanley, Cadbury’s adviser, the bank ratcheted up the interest rate on the debt package, according to people close to the matter. For the private equity titans, this unusual behaviour was a confirmation of their worst fears: the world had fundamentally changed, and not in their favour.