Senior Conservative ministers have been rebuked for attempting to cover up Government statistics showing one of their key housing policies is not working.

While serving in opposition, the shadow Housing minister, Grant Shapps, promised Tory backing for people who built their own homes to kick-start a house building “revolution” in the UK.

Two years later in Government, he launched an action plan to double the number of self-build homes within a decade.

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But when Labour attempted to find out how the Government was getting on with its pledge, senior officials in the Department of Communities and Local Government (DCLG) attempted to prevent the release of statistics showing how many self-build homes had been started.

Bizarrely, they tried to claim that they could not provide the information because to do so would “prejudice the effective conduct of public affairs”.

“Officials and Ministers need a safe space in which they can offer free and frank advice and exchange [of] views,” they wrote. “It is reasonable to acknowledge that data from a variety of sources will form an important part of this essential process and therefore should have the same degree of protection as other information.

“If this data was made available at a premature stage it would result in weaker discussions, poorer decision-making and the closure of policy options.”

Not surprisingly, aides of the now shadow Housing minister, Hilary Benn, were a little surprised at the decision and lodged an appeal with the Information Commissioner.

In his ruling, seen by The Independent, the Commissioner roundly rejected the argument put forward by DCLG officials and demanded that the information be released.

“The exemptions cited by DCLG require more than the possible inconvenience in responding to queries about disclosures,” he wrote scathingly.

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“The Commissioner considers that DCLG has not provided arguments which demonstrate that disclosure would inhibit the free and frank provision of advice or the free and frank exchange of views for the purposes of deliberation.”

He ordered the information be released.

And what did it show? In a short table released to Labour it showed that the number of people who begin self-build homes had fallen since the depths of the recession in 2009 under Labour from 11,800 to 10,400 in 2011.

Oddly the department claimed it did not hold the statistics for 2012 – despite the fact that more than five months had elapsed since the period covered by the data.

Labour claimed the episode had echoes of previous attempts to suppress uncomfortable information by DCLG – which it said was a waste of public money and civil servants’ time.

Earlier this month The Independent revealed that the Department had spent thousands of pound attempting to suppress internal emails which showed officials in the department believed Mr Shapps may have misled MPs.

When they were finally forced to back down by the Information Commissioner and release the emails they showed that civil servants believed Mr Shapps, who is now Conservative Party chairman, had made inaccurate statements about the number of affordable homes being built in Britain.

Last night Mr Benn said that the latest episode appeared to show similar form.

“Eric Pickles has yet again wasted public money on trying to suppress evidence of the failure of his and Grant Shapps’ ‘self-build revolution’,” he said.

“He attempted – and failed – to use the ministerial veto as a way of not disclosing these basic statistics. Mr Pickles likes to lecture councils on the virtues of transparency, but as this case shows he’s not really very keen on it himself.”

A spokesman for the Department for Communities and Local Government said: “The Government does not produce official statistics on self-build and the crude estimates we have had methodological flaws, which is why we did not release them.

“However, we remain determined to help the self-build industry double in size over the next decade, which is why we’ve made £44m available to provide short-term loans to help community groups get their self-build projects off the ground, made public land available to accommodate self -build and why our reforms require councils to consider the needs of self-builders when drawing up their local plans.”