This stands a chance of being the most surreal and weird thing an MP has ever revealed about their spare time (yes, even stranger than 'running through fields of wheat') but a little digging revealed that this wasn't the first time that he had mentioned this unusual pass time.
In a 2011 interview with Metro, when Johnson was still the mayor of London, he told the newspaper that rather than wine boxes he used cheese boxes and would paint them to resemble famous locations like the Rome Colosseum.
I like to relax by painting on cheese boxes. You get Brie and Camembert in these lovely wooden boxes. Now it might sound cretinous and I'm not a very good painter but I enjoy it and find it therapeutic.
I paint the whole thing white with a tube of children's paint and I look for something to paint. The last thing I painted was a picture of my family in front of the Colosseum in Rome. I also like painting whisky bottles.
If you thought that was weird wait until you read the rest of the interview. When asked who he admired the most, he named Avengers star Scarlett Johansson, as well as Marilyn Monroe and the Greek philosopher, Aristotle, along with his wife, Marina Wheeler, who he divorced from in 2018.
Aristotle, Marilyn Monroe, and Scarlett Johansson, in fact, I think she might have overtaken Marilyn Monroe and my wife, of course. My wife is way ahead of Aristotle. She's beaten him in the final furlong.
He then elaborates on his admiration of Aristotle.
Aristotle believes that everything is aimed at eudaimonia [happiness] but the way to get there is to apply phronesis, which is a kind of moral wisdom.
He's a brilliant moral philosopher. He also wrote very well on the sex life of cuttlefish and other important subjects.
He was the first great Renaissance man he was interested in everything but everything in moderation.
As it would turn out Johnson has quite an affection for Ancient Greece, as he named Pericles as his favourite politician.
Pericles [495-429BC, a general of Athens]. He's famous for explaining why democracy is the best form of government.
He talked about what made Athens special. He said we have a democracy and in a democracy anyone from any background can make it and his was the first articulation of that in the world.
That speech still reads brilliantly. You could put it on the lips of any politician today.
When asked what his greatest fear is he said 'bad things happening to his loved ones' which is fair enough but kinda vague and said that his biggest regret was not learning to play the piano.
I regret not really cudgelling myself through the piano. I could have been a contender. I only got to Grade 1 and that was after I failed once.
His guilty pleasure isn't exactly what you would have in mind either.
I've been secretly watching the complete series of Colditz, which was produced by the BBC in the 1970s and it is an absolutely brilliant historical document because it is basically a concealed piece of pro-Euro propaganda.
Then there's mudlarking. I picked up a sheep's jaw, a pig's rib, a piece of ancient pot and a Victoria pipe while mudlarking [along the Thames]. People don't know what treasures are being washed up on the banks of that great river every day.
A historic bounty is running right through this great city and if I wasn't busy running it I'd be down there with those mudlarks right now.
The rest of the interview is the sort of mundane and by-the-numbers stuff that you would expect of a politician but the cheese boxes and Scarlett Johansson stuff? By golly?