Disturbance adds to burden of leaderless force

When Sir Paul Stephenson resigned as Metropolitan Police Commissioner last month, in the wake of the phone-hacking scandal, he said the force faced a year of "enormous challenges that are the staple diet of this incredible organisation".

To this long list of challenges – phone hacking, the 2012 Olympics, and 20 per cent budget cuts – could be added the riots in Tottenham last night.

The images of police cars ablaze and the most serious civil disturbances in the capital for several years emphasised how exposed Scotland Yard now seems.

There could not be a worse time for Britain's busiest force to be without a chief. Acting Commissioner Tim Godwin has a new Deputy Commissioner, Bernard Hogan-Howe, at his side, but there are already reports of wrangling between David Cameron and Home Secretary Theresa May over a successor to Sir Paul (pictured).

The scandal also claimed John Yates, Scotland Yard's head of counter-terrorism – who, in a veiled swipe at his critics, suggested the force should be focusing on protecting London's streets.

Sir Paul's resignation statement listed the success of policing the royal wedding in April, a 10-year low in crime, and his force's "restrained" approach to student demonstrations. The reality is police were caught off-guard by the levels of violence in the first protest, then criticised for being too heavy handed in later demonstrations. Questions will now be asked whether, after last week's shooting of Mark Duggan – the apparent trigger for the riots – Scotland Yard was fully prepared.