David Cameron has come under fire for making a speech from outside Downing Street about the dangers of quitting the European Union – despite a ban on the use of government resources in the final run-up to this week's referendum.
To ensure a fair campaign, civil servants and government ministers have been given strict guidelines on their conduct ahead of Thursday's vote on whether to stay in or leave the EU.
The rules for the 28-day pre-referendum period, often referred to as "purdah", place curbs on the use of government property for campaign purposes, and make clear that both sides of the debate are only able to draw on civil servants for normal departmental business and not on any matters relating to the EU vote.
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But Cameron sparked criticism from the Leave camp on Tuesday when he used a hastily-arranged speech outside Number 10 Downing Street to stress the Remain campaign's key message that the British economy would suffer if British voters backed Brexit, an outcome he said would pose "a risk to our children's future".
The prime minister said: "We have the best of both worlds, so as you take this decision whether to remain or leave, do think about the hopes and dreams of your children and grandchildren – they know their chances to work, to travel, to build the sort of open society they want to live in rest on this outcome."
But Bernard Jenkin, the Conservative chair of parliament's Public Administration and Constitutional Affairs Committee (PACAC) and a key Vote Leave campaigner, told CSW that the move was "without doubt a breach of the spirit of purdah" which would not have been tolerated in the run-up to a general election.
He added: "It is another desperate ploy to try and get on the news agenda when the Leave campaign is dominating the news agenda."
A Downing Street spokesperson told CSW's sister site PoliticsHome: "We took advice and are confident it falls within purdah rules".
It is understood that Number 10's status as Cameron's official residence means it may be exempt from the purdah rules – and the podium from which Cameron gave his address did not bear the official logo of the prime minister's office.
But Jenkin said the press conference was "clearly" intended to give the impression of Cameron "speaking as prime minister, not as a Remain campaigner".
"And that is a breach of purdah because ministers are not meant to publish anything during the referendum period as ministers," he added.
Jenkin has been particularly focused on the use of government resources during the referendum campaign, last year leading a rebellion of Conservative MPs that prompted to the government to shelve its initial plans to axe the 28-day purdah period.
His committee also questioned cabinet secretary Sir Jeremy Heywood over guidance issued to civil servants on the support they were able to pro-Brexit ministers, after concerns that the rules skewed the campaign in favour of the Remain side.