Engaged in a lively question-and-answer session with a group of workers - it probably seemed like another perfect photo opportunity for David Cameron.
Alas, it was not to be.
As Cameron spoke to the crowd at Utility Warehouse in Hendon, north-west London, one worker was keen to show his true colours - and they certainly didn’t involve any Tory blue.

Is it us or is this a TINY bit creepy?
As the group appears to listen intently, the man turned around to reveal a Ukip rosette.
Dressed aptly in Ukip purple and wearing a knowing smile, the man stared straight into the camera as the PM and his fellow workers carried on unaware.
It is unclear if photobombing is part of the anti-EU party’s last-minute campaigning tactics or if this activist was simply a lone wolf.
Could it be that Nigel Farage may have taken inspiration from an incident last year when he himself became a photobomb victim?
The Ukip leader was snapped being followed by a man dressed as Jesus, who repeatedly gave him the thumbs-down.
Mr Cameron seemed blissfully unaware of today’s incident, however, taking part in a question-and-answer session with workers at the company, accompanied by Boris Johnson.
He dismissed jibes about elitism and urged people to back the Conservatives to avoid a disastrous tie-up between Labour and the SNP.
But he stressed that he had acted to give the UK "strong government" by allying with the Liberal Democrats in 2010.
Asked to give a view on the constitutional position if no one party had a majority on Friday, Mr Cameron replied: "You are in the prediction business and you can make lots of predictions in the next 36 hours.
GENERAL ELECTION 2015
"I tell you what I am in, I am in the business of saying to people ... don't talk about predicting the future - shape the future with your vote.
"There is still time to determine the outcome of this election."
But after a member of the audience complained that politicians never gave straight answers, he added: "I put the country first, I formed a coalition. I did what was right to give strong government for Britain. So I will always put the country first."