You could tell the presenter of the London edition of BBC One's Sunday Politics was a bit nonplussed to reveal that his guest this week was not Boris Johnson. Instead it was the Mayor's deputy, Kit Malthouse, who stepped up to bat on Boris' behalf.
Obviously it's not ideal for the BBC, which gets flack over political balance more than any other media organisation in Britain. Ken Livingstone, Brian Paddick and Jenny Jones have all appeared on the programme in recent weeks.
The Tory Mayor - whose poll lead over Ken Livingstone shrank to within the margin of error over the last week - apparently told the programme weeks ago that he couldn't attend due to a "private engagement". But Dave Hill, the Guardian's eagle-eyed observer of London politics, took to Twitter to track down Boris' movements, and struck gold.
For it appears that Boris' private engagement turned out to be campaigning in Wimbledon - a fairly affluent part of London where he really needs to get the vote out if he's to win. And there is Twitter evidence in abundance...
What does this tell us about Boris' tactics? Hill describes the narrative by Team Boris as "deeply unsatisfactory".
A BBC source told HuffPost that Boris' appearance had never been confirmed. But 180,000 people watch the London edition of The Sunday Politics, so that's quite a lot of Londoners. Does it suggest that the air war is over and it's all down to getting the vote out on the ground at this stage in the campaign?
The latest YouGov poll - released on Monday morning - suggests Boris has a 4% lead over Ken. That's only just outside the margin of error, but up on last week's poll where the gap was just 2%.
Peter Kellner, President of YouGov, spoke to HuffPost on Monday morning, telling us he thought it was the right call to stay off the airwaves.
"Had I been Boris’s strategist - which, thank the Lord, I’m not, sir - I would have given him this advice last week: 'You are narrowly ahead in the polls. The main thing now is not to make any gaffes.
"Close interrogation on the Sunday Politics can do you no good. Too few people watch it. But if you go on and slip up, the rest of the media would jump on you. Instead, go somewhere that might help you get out your vote – say, Wimbledon.'
"I have no idea whether that is the advice Boris received; but from his point of view, he made the right decision."
HuffPost also spoke to Patrick Dunleavy - professor of political science at the LSE - on Monday morning. He finds Boris' campaign a "puzzle" - and thinks what's been a poor campaign might not be entirely accidental:
"It's been almost non-existent and what there has been has been ineffective or counter-productive - such as doorstep campaigning, and then suddenly popping up in the Telegraph demanding tax cuts and, shoring up his support on the right - when what he needs to do is stop the centre deserting him.
"If you look at things from Boris' point of view, supposing your job was to advise him how to become PM as soon as possible. Would he be better off losing on Thursday, despite gallantly campaigning on the doorstep - unavailingly?
"He could then rest up for a few months and look for a safe seat in the Commons - certain to get back. Then when coalition begins to folds early in 2013 or 2014 - as it must - he is in pole position to become Tory leader.
"By contrast, if he locks in for four more hopeless years as Mayor he is in a poor position when Cameron folds and he is not an MP.
"So I can't help thinking that Boris is trying to be ineffective but at the same time hard-working - a gallant loser who could not quite stem the anti-Tory tide, but still performed say 16% better than his party."
UPDATE: The BBC has told us that Boris will be appearing on the Daily Politics on BBC Two on Tuesday at Noon.
London votes this Thursday, May the 3rd. The full candidates in this election are: