Mr Pritchard said the newspaper had used "questionable techniques" to obtain explicit pictures from fellow Conservative Brooks Newmark who resigned from his post in the Cabinet Office.
In the sting, a male freelance reporter adopted the false identity of "Sophie Wittams" and set up a Twitter account describing himself as a "twenty-something Tory PR girl".
Following flattering messages from the mysterious Ms Wittams, Mr Newmark agreed to swap "sexually explicit images".
But, of course, Mr Newmark did not receive an image in return of Ms Wittams, instead receiving a "sunbathing selfie" of Charlene Tyler, a 26-year-old from Boston in Lincolnshire.
Ms Tyler told the Daily Telegraph yesterday it was wrong for the paper to have used her photo without permission, and that Mr Newmark had done nothing wrong.
However, this was not the only image to have been used by the freelancer without permission.
The avatar of the fictional Twitter account with which Mr Newmark communicated was a picture of Swedish model Malin Sahlén.
And she has told Swedish newspaper Aftonbladet: “I do not want to be exploited in this way and that someone has used my image like this feels really awful, both for me and the others involved in this.
“I am shocked and it is unpleasant for someone to use the picture without permission.”
Sunday Mirror editor-in-chief Lloyd Embley has now apologised to both women, explaining: “We thought that pictures used by the investigation were posed by models, but we now know that some real pictures were used.
"At no point has the Sunday Mirror published any of these images, but we would like to apologise to the women involved for their use in the investigation."
Nevertheless, the newspaper boss stood by the story, claiming it was in the public interest.
The public interest defence is much used by newspapers and, in this case, it mainly relates to Mr Newmark's role as co-founder of the Women2Win organisation.
Women2Win is aimed at attracting more Conservative women to Parliament - and the Sunday Mirror will argue Mr Newmark's conduct contradicts this position.
Based on previous rulings, though, the newspaper would appear to have a pretty weak case, if nothing else because of the use of entrapment.
"Fishing expeditions", as they are known, must surely carry a more substantial public interest argument than this. Even the Sun and the Mail have said they turned the story down.
Ultimately, the article has done no favours to any of the parties involved. Mr Newmark has lost his ministerial salary and must try to rebuild trust with his wife and five children.
Meanwhile, the Conservatives have suffered an awful start to their party conference in Birmingham, a double-whammy coming in the form of Mark Reckless's decision to defect to UKIP.
MP for Rochester and Stroud, Mr Reckless became the second Tory to resign and seek re-election on the UKIP platform after Douglas Carswell's move in Clacton just over a month ago.
Finally, this story has done nothing to rebuild the already-pathetically low levels of trust between the national press and the public.
Coincidentally, it came at the end of a week in which it became apparent the same Trinity Mirror group of newspapers was also heavily involved in phone-hacking.
Phone-hacking, fishing expeditions, honey-traps - all of them are bound to produce a juicy story - but are any of them actually news?
Proper journalism sticks to the facts of what has actually happened or discloses serious levels of hypocrisy and/or incompetence.
It does not seek to manufacture the story for its own monetary gain.
