Boris Johnson is facing his first big policy obstacle as Mayor of London after the Information Commissioner objected to his plans to map crime in the capital street by street, The Times has learnt.

Crime mapping, whereby details of offences and convictions would be published for every neighbourhood in the capital, was an integral aspect of the mayor's crime manifesto.

However, its implementation has been delayed after concerns were raised about data protection and the privacy of victims. The property industry has also expressed misgivings, with fears that already ailing housing prices could be affected.

During the election campaign Mr Johnson pledged to make crime data available more widely and believes that crime mapping would help London residents to hold their local police to account.

Despite the setbacks, the mayor remains determined to introduce the policy. City Hall sources told The Times that senior Metropolitan Police officers believed that they had found a way around the Information Commissioner's privacy issues. However, it may mean that the crime-mapping initiative is not as specific as Mr Johnson intended originally.

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