The MP paused to check his phone, sighed, and turned casually to a colleague waiting at the same lift in Portcullis House. Boris is inviting me for a chat, he confided. I havent made my mind up yet, what do you think?
They talked in murmurs for a minute before the MP checked his phone again and remembered an appointment. He slipped away leaving his more innocent colleague unaware he had been expertly interrogated by a sleeper. In the shady world of subterfuge and suspicion that makes a Tory leadership contest, the Sleeper is one of a cast of characters who inhabit Westminster.
Low-profile MPs who affect to be open-minded, their job is to draw others into unguarded revelations. Sleepers were used by John Majors team in 1995 to sniff out MPs who had falsely sworn loyalty to him while secretly backing John Redwood. They use your friends to test you, scowled a Brexiteer who has learned to be wary of approaches.
Le Carr takes over from Erskine May as a source of parliamentary tradecraft. Another ruse is the false coat trail, when an MP purports to be drumming up support for, say, Jeremy Hunt, while really reporting reactions back to Michael Gove. The trick might winkle out the ambitious backbencher who tries to ingratiate himself with more than one candidate.
An ex-minister who has taken part in four leadership contests is blunt. Any candidate who doesnt have a decent intelligence network deserves to be humiliated and probably will be. The parliamentary Conservative Party has been called the most sophisticated electorate in the world, which is a polite way of saying bare-faced liars.
How MPs voted in the secret ballot between 10am and 12pm today may bear no relation to what they declared in public or promised in private. It is why less experienced campaign managers were dreading this afternoons opening of the ballot box, when their ability to assess the numbers would be laid bare. Some have far fewer supporters than they assured their candidate would be the case.
More is at stake than reputations, because knowing when to jump off a crashing bandwagon is vital. A candidate who might yesterday have traded his endorsement in return for a promotion will have no leverage if eliminated unexpectedly. Some have big decisions to make about whether to cash in their chips, said a rival teams adviser.
They might pick up more votes, but they could lose votes between now and the second ballot. The reality is that most MPs will now gravitate to the frontrunners. The godfather of the numbers game is Lyndon B Johnson, 36th US president, whose rule was learn to count.
The textbook is Robert Caros Master of the Senate which describes LBJs meticulous vote-counting techniques that won him influence and victories. If a potential recruit is identified, it is reported back to the numbers man at HQ. Boris Johnsons team is managed by ex-MP James Wharton, but he also has the services of former defence secretary Gavin Williamson, who has a chief whips counting ability.
A campaign manager may flatter a target with an invitation to meet the candidate. Michael Goves manager Mel Stride holds discreet dinners at his home and is said to serve the best food and wine of any of the campaigns. Another technique is blitzing, where an MP is bombarded with a propaganda message.
It worked for Tony Blair in 1994, but is seen as counter-productive by seasoned Tory campaigners. The master list records supporters, hopefuls and those who might transfer later. Accuracy is vital: no time to waste on MPs who cant be persuaded.
Secrecy is essential: rivals are fighting for the same intelligence. Francis Maude stores the list he kept for Mr Majors 1990 bid in a bank vault. Cross-checking is important.
Some MPs give false promises because they are scared to say no if a big beast corners them. Others do so out of ambition. After the 2016 race, rival whips compared notes and found a North-West MP had guaranteed his ballot to each of them.
Security is paramount. After crashing out in the first round of the 1997 contest, Peter Lilley realised there had been a spy in his camp when the votes were counted and he had one fewer than the number of MPs on his team. With a third of Tory MPs yet to reveal their intentions in public, nothing can be taken for granted.
Which is why, for the next seven days, Westminster will resemble East Berlin.