The Department of Education is notoriously bad at answering freedom of information requests, even being put under special monitoring by the information commissioner's office  in December last year because of past inadequacies in answering queries. So it's doubly impressive that Janet Downs, a retired teacher and campaigner who is part of the Local Schools Network , not only managed to get an answer from them, but also extract an excruciating confession about what passes for "evidence" in Michael Gove's department.
Querying a claim made in article in the Mail on Sunday titled "I refuse to surrender to the Marxist teachers hell-bent on destroying our schools: Education Secretary berates 'the new enemies of promise' for opposing his plans ", Downs asked for the background to Gove's claim  that:
Survey after survey has revealed disturbing historical ignorance, with one teenager in five believing Winston Churchill was a fictional character while 58 per cent think Sherlock Holmes was real.
The department revealed that the main claim sources from a survey "commissioned and conducted by UKTV Gold", and that the other surveys referred to include:
- a survey of 2000 11 to 16 year olds by Premier Inn;
- a study commissioned by Lord Ashcroft of 1000 children aged 11 to 18 to mark the unveiling of the Bomber Command Memorial in London;
- a report by Professor Robert Tombs for think-tank Politeia;
- an article by London Mums Magazine ;
- research carried out by the Sea Cadets to mark the anniversary of the Battle of Trafalgar .
That last survey was linked, by the Department of Education, to an article in the Telegraph, rather than the initial survey.
To be clear, five of the six "surveys" cited by the Department of Education in backing up a claim by a cabinet minister were PR-commissioned puff-polls. They were commissioned, not to find out information in a trustworthy and repeatable manner, but to ensure that stories about UKTV Gold, Premier Inn, the Sea Cadets , Bomber Command Memorial and "teacher-set exam revision service" Education Quizzes found their way into UK papers. Some of them may additionally be respectable polling – the Lord Ashcroft poll around Bomber Memorial Command  uses a nationally representative sample, non-leading questions, and face-to-face interviews, for instance – but it's the sort of thing which normally rings alarm bells.
The last cited survey isn't a survey. It's a pamphlet on "Freedom, Aspiration and the New Curriculum " from think-tank Politeia. While it agrees with Gove's conclusion, it is hardly a primary source (an ironic distinction to have to make in a discussion about history teaching).
If this the sort of information which is revealed when the Department of Education responds to freedom of information requests, it's becoming clearer why they so rarely do it.