Labour’s deputy leader accused Gove of being evasive to the media and said the controversy was causing embarrassment for the royal family.
The intervention will pile pressure on the justice secretary, who was one of a handful of people at the lunch where the Queen was alleged to have aired Eurosceptic views to the then deputy prime minister, Nick Clegg.
The palace put in a complaint to IPSO about the story, with rumours suggesting Gove was the main source.
The Sun claimed the conversation suggested she would back Brexit, but the palace insisted she was politically neutral, saying the referendum had not been agreed at the time the event allegedly took place and Brexit as a phrase had not been coined. Clegg said the story was “nonsense”.
Watson said: “We live in a constitutional monarchy and convention dictates that the Queen, unlike elected politicians, is unable to engage in public debate through the media.
“It has been suggested that Michael Gove has revealed to the Sun newspaper details of a private conversation between him and the Queen ... Given that [the Sun editor] cannot reveal the Sun’s sources for the story, which appears to be based on a number of conversations, it is incumbent on Michael Gove to categorically confirm or deny whether he revealed the content of one of them.”
He added: “This is a time for clarity and he needs to answer the simple question: are you a Sun source or not Mr Gove? Yes or no?”
It came after Alastair Campbell, Tony Blair’s former spin doctor, said his time working with the royals told him that the story was “cock” because otherwise there would not have been a complaint.
This article was written by Anushka Asthana Political editor, for theguardian.com on Sunday 13th March 2016 16.14 Europe/Londonguardian.co.uk © Guardian News and Media Limited 2010