The pictures of blazing buildings in Tottenham, Hackney, Croydon and Ealing look likely to become the defining images of David Cameron's early days in Downing Street.

Now he faces a massive test of his leadership qualities as the Government and police attempt to bring the lawlessness under control. If the violence continues, Mr Cameron's reputation will suffer a blow from which it could be impossible to recover.

Mr Cameron always knew he would have to push through spending cuts, attempt to rebuild the economy and cope with opposition to widespread job losses.

For all his warnings about "broken Britain", what he could not have prepared for is the biggest wave of criminality in living memory – just as the police service faces swingeing cuts.

In the first 48 hours of the crisis, the Prime Minister appeared behind the curve, despite Downing Street's insistence that he was being updated hourly in Tuscany.

As late as 8pm on Monday night, No 10 was arguing that there was no need from him to return. By that time trouble had broken out in Hackney and Lewisham and shops across the capital, from Barnet to Croydon, were closing early in anticipation of violence.

There was an air of panic as Mr Cameron was finally scrambled yesterday on to a military aircraft back to Britain and a meeting of the Cobra emergency committee.

He decided to throw resources at the problem – more than doubling the capital's police presence. It was a move that would have been welcomed 12 hours earlier in areas such as Clapham, Woolwich and East Dulwich, where looters went unchallenged much of the night.

He will hope that the sheer force of police numbers will ensure the disturbances are short-lived.

The Home Secretary Theresa May also faces her first severe challenge. She has been praised for her cool efficiency, but seemed rattled and defensive in interviews yesterday. If their attempt to get a grip on the emergency succeeds, the questions will turn to the causes of the violence, with the Tory Right pressing for tougher punishment of the law-breakers. If they fail, Mr Cameron will face searching questions over his competence.