Gordon Brown recently wrote to David Davis to say this:
As you know, Prime Ministers are available once a week at Question Time to debate all the issues of the day, and I was disappointed that you chose to step down as a Member of Parliament in advance of Question Time on Wednesday, 11 June rather than coming to the House to debate with me the issues around the use of CCTV and DNA evidence, and the measures we have taken to protect our national security.
Nevertheless, the leader of your party has the opportunity each week to ask six questions on those issues that caused you to leave his Shadow Cabinet. He has had two such opportunities to date, but he has yet to ask any such question. He has two further opportunities to raise these issues before the 'by-election' on July 10th, and I am sure that if he shares your strong feelings about them, he will not duck those opportunities.
David Davis has replied, with a masterful letter:
Thank you for your letter of 26 June. This is the second time you have responded to me directly, since my resignation from the House of Commons in protest at your relentless assault on British liberty.
First, you gave a speech on 17 June at the IPPR, a favoured Labour think-tank, hardly an environment that allows for the vigorous and open debate we so sorely need. Now, you insist that any questions I wish to ask on this vital national issue be raised within the narrow confines of Prime Ministers Questions, where you have developed the novel practice of asking - rather than answering- the questions.
I note from your speech on 17 June that you genuinely believe in the positions you have taken and stand behind the sustained erosion on British liberty, which regrettably means that the country must expect more to come in the future. Equally, it is deeply disturbing how ill-informed you are about the basic effectiveness of your security policies - from 42 days, ID cards and the DNA database, through to the ineffectual deployment of CCTV at immense cost to the taxpayer.
We need a proper national debate on these important matters - not just set piece speeches to carefully choreographed audiences or the weekly one-liners you deploy at PMQs. If you were serious about debating these important issues, you should have put up a candidate or at the very least allowed your Ministers to debate publicly with me. Having cowered from both options, it is a bit rich to snipe from the sidelines in a serious debate that will proceed with or without you. Even at this late stage, I would be only too willing to adjust my schedule to debate you or any Cabinet Minister in public, if you feel able to relax the restrictions currently in place.
In short, Brown has said "You lost an opportunity to 'debate', but you should have got more support, nah nah ne nah nah." and Davis is saying "Anytime, Any place, Anywhere - bring it on".