Chairman of the 1922 Committee Graham Brady makes a statement to reporters in Westminster. Photo: PA
As befits the most senior Conservative backbencher, Sir Graham Brady has a nice office. It's a corner room, high up in Portcullis House, which affords its occupant rather more space than some of his colleagues and a wonderful view. Somewhere within that room sits a stack of extremely important letters.
In his capacity as Chairman of the 1922 Committee, the representative body of backbench Tory MPs, guarding those letters is Brady's most solemn duty. Each one represents a Conservative MP's formal request for a vote of no confidence in their leader.
Under the Party's rules, one such letter on its own has no effect—but if the total passes the key threshold of 15 per cent of the Parliamentary Conservative Party, then a confidence ballot of MPs is automatically triggered.
The precise number of letters therefore matters a lot. In 2003, it only took 25 MPs to trigger the ballot that defenestrated Iain Duncan Smith. Today, with many more Tory MPs, the threshold sits at 48.
Crucially, only Brady knows how many letters are in his possession. Once submitted, he holds a letter indefinitely, unless its owner withdraws it. Occasionally people choose to go public, as Andrew Bridgen did when he wrote to Brady in 2013 and took his letter back seven months later, but normally the submission and withdrawal of letters happen in complete secrecy.
That secrecy protects MPs from punishment for disloyalty, while the uncertainty over how many more letters are needed guards the leader from whimsical rebellion or precisely-calculated threats.
Just like the nation's organic constitution, so beloved of Conservatives, this arrangement looks barmy but it broadly works; it is a Heath Robinson contraption that manages to balance competing interests quite effectively. And it all rests on trust in Brady's word, which he takes very seriously indeed.
Rumours of exactly how many letters Sir Graham has should therefore be taken with a pinch of salt. Given his position and his sense of honour, he is very unlikely to have told anyone the figure, particularly if, as some have speculated, it is approaching the threshold.
Recent reports claim that he is said to have "intimated" the threshold might be close, partially through appearing "ashen-faced" at the prospect of receiving more letters—which is far from confirmation of a specific number. These claims probably come from good sources, who likely believe their figures, but they're based on guesswork.
Such guesses may be right, but are just as likely to be wrong. Conservative MPs are euphemistically called "the most sophisticated electorate in the world"—they can be unpredictable, inscrutable, clannish and changeable, and are sometimes all of those things before breakfast.
Some people go to great lengths of Kremlinology to tally up who has probably written a letter, who might be considering it, which groups or factions might me mobilising, and so on. But guesstimates are inherently imprecise.
Theresa May is certainly in danger; she has been since her snap General Election backfired. The threat ebbs and flows: her conference speech exacerbated it, while her success in securing agreement on 'sufficient progress' in the Brexit talks reduced it.
Her position is protected by the belief that a new leadership contest (and it would have to be a proper contest) would disrupt the mission of delivering Brexit, and the fear that a contest might accidentally result in another election. These factors are powerful, but they are not insurmountable.
If the Prime Minister comes to be seen as more harmful than those alternatives—for example, by appearing to betray Leave voters, or developing a serious belief that she should lead her Party into the next election—then the whole situation could turn on a sixpence.
The precise tally of letters is unknown. More interesting is the question of who has chosen to whisper that it is teetering close to the threshold, and why. Maybe someone is showing off their guesswork. Perhaps one faction or another hopes to make May more pliable by putting her on notice. Maybe the Parliamentary Conservative Party really is on the verge of a no confidence vote, by accident or design.
Or might someone be reminding Tory MPs of the dangers of disloyalty: do you really want to be the person who plunged us all into chaos, and put Corbyn into power?
Confronted with that possibility, MPs might think twice about writing new letters, or might withdraw those currently on file. In this unpredictable system, hyping up the threat of rebellion can sometimes strengthen a leader's position.
