Last week Full Fact raised concerns over the way transport crime figures were issued by Mayor of London Boris Johnson to the press but not to the public.

The statistics, showing a reduction in the number of crimes on the capital's transport network, were collated for a media event hosted by Mr Johnson, at least two weeks ahead of the full publication of the latest quarterly update of the figures.

One of our core principles at Full Fact is that if politicians make a claim, the full information behind it should be available for the public to check.

It is not only a principle held by us but one that is, to an extent, enshrined in the Code of Practice for Official Statistics.

This states that bodies producing official statistics should “Issue statistical reports separately from any other statement or comment about the figures and ensure that no statement or comment – based on prior knowledge – is issued to the press or published ahead of the publication of the statistics.”

Having consulted the UK Statistics Authority on the matter it appears there is no action that the Authority can take in this case.

We were told that the use of official statistics in a press notice ahead of the scheduled publication date of the statistics would be a breach of the Code of Practice.

However at present figures neither Transport for London, not the Metropolitan Police are considered producers of official statistics. As such, any action relating to these statistics can not be in breach of the Code and is therefore beyond the remit of the Authority.

Despite the lack of rules governing the figures used by the Mayor, we feel that this statistical good practice should be adhered to though there is no compulsion to do so.

It is of concern that such a politically resonant figures can be produced and used without adhering to these standards and we will be looking for an opportunity to change this

The Authority have told us they will be flagging the issue up with the national statistician as part of a review of crime statistics.