Prime Minister David Cameron was made to explain himself in the Commons on Wednesday after PMQs, because of a complaint from a Labour MP.

Bolton West MP Julie Hilling complained that the Prime Minister was wrong to describe her as “sponsored by Unite”, when answering a question from her at Prime Minister’s Questions.

Cameron was dragged back to his seat as he tried to leave, to answer the alleged factual inaccuracy. Labour MPs howled in protest as the PM tried to exit the chamber behind the Speaker's chair.

He defended himself by quoting the Register of Members’ Interests. He said that Hilling had received £2,250 from the trade union in 2010, and a similar donation to her constituency office.

John Bercow told Hilling that he didn’t feel being “sponsored” by Unite was a matter to be considered by the Speaker as a point of order.

The reality is slightly more complex. Unite was not Hilling's largest donor, that comes from another union, the Transport Salaried Staffs Association, who gave her £7,000 in 2010. Unite gave the Labour MP £2,250. Both of these are listed as "sponsorships" in Hilling's register of MPs interests.

This is confirmed on Parliament's website, where Unite's donation is clearly listed as a sponsorship.

Tory MP Matthew Hancock has recently unearthed further evidence of Hilling's relationship with Unite:

@matthancockmp
Matthew Hancock

Hansard of Julie Hilling declaring her interest in Unite the union, to her Select Ctte - why hide at PMQs? http://t.co/30mUcWfb

February 29, 2012 1:26 pm via Photos on iOS Reply Retweet Favorite

And a quick search of Hansard shows that in November 2010 Julie Hilling said in a Westminster Hall debate on the Youth sector:

"I have a vested interest in this debate, in that I have spent almost all my working life as a youth and community worker, and Unite supported me in my election campaign."

However speaking to Politicshome.com Hilling has insisted that this money does not constitute sponsorship. She said: "That is like saying if a Tory gets a donation from a business, he is sponsored by them."