Scottish independence: Ed Miliband's wife Justine Thornton hits the campaign trail alone

Justine Thornton with her husband, Labour leader Ed Miliband (Getty Images)

Justine Thornton, the wife of Ed Miliband, will emerge from the shadows tomorrow when she campaigns against Scottish independence.

The environmental lawyer will tour Glasgow in the Labour Party’s referendum battlebus, meet ordinary people and go door-to-door canvassing in support of the Better Together campaign.

Tonight, Ms Thornton attended the opening ceremony of the Commonwealth Games with Mr Miliband. The significance of tomorrow's event is that she will be campaigning in her own right, meaning that the Labour leader will not accompany her.

A Labour source said that she wanted to campaign on the issue because “she feels strongly that the UK should stick together.” He added: “She won’t make a formal speech, but she will be out on the stump.”

Her intervention in the Scottish debate marks the start of a process which will put her increasingly in the public spotlight in the run-up to next May’s general election.

Ms Thornton has been reluctant to become a public figure. She is now ready to take on a more prominent role to boost Mr Miliband’s election prospects – but wants to do it in her own right rather than as a “politician’s wife.”

Friends describe her as independent-minded with strong views.

Labour politicians who have heard her speak at private functions describe her as a “brilliant speaker” who could be a “huge asset” to Labour. They believe her higher profile will help to tackle Mr Miliband’s image problem.

There is speculation that Ms Thornton will play a big role at the Labour conference in September. Sarah Brown, the wife of Prime Minister Gordon Brown, introduced him at Labour’s 2009 conference.