You would think that someone with a name like Alexander Boris de Pfeffel Johnson would eat like a forward-thinking king. I’m talking hearty, experimental, well-sourced, nutritionally balanced meals all cooked up by a private chef – not ‘yum, bring on my next gout flare-up’ recipes, like older kings. You’d assume that, like all Tories, he could demand hand-whipped butter and fresh sourdough balanced with the freshest, sweetest asparagus and petits pois and it would just appear. But no, instead he eats a less varied diet than you or I (someone who could survive off the McDonald’s Savers Menu if it were socially acceptable).

So what does Britain's current, unelected overlord Alexander Boris de Pfeffel Johnson actually eat? He took part in the Observer’s ‘What’s in your basket?’ series, which boasts a wonderfully deranged range of contributors from Adele, Lindsay Lohan and Steven Seagal to Gok Wan. And readers at the time – in 2008, just before he became Mayor of London – learned that aside from an apparent aversion to fruits and vegetables, he doesn’t eat anything that wild.

But there are a few things to note from his Observer Food Monthly diet diary. First, Johnson said that he’d have a slice of birthday cake for breakfast because they’re often leftover in the fridge. An immediate question arises: why, are how, are there so many birthdays in the Johnson household?

Beyond that, you also also find out that his favourite meal is bangers and mash. Most recently, Iceland – one of the least Tory supermarkets – hand-delivered all the ingredients needed to make a couple of servings of it to No. 10, along with a note that read: “The British public can also be safe in the knowledge that by buying frozen, Boris could also save 47 percent on his food expenses – a winning deal for everyone.” Lovely. For anyone still obsessed with comparing Johnson to Donald Trump, Alexander Boris de Pfeffel said he drank at least a litre of Diet Coke a day, while Trump reportedly gets through 12 cans a day. Draw your own conclusions, have your own fun etc etc.

Finally, Johnson went on to talk about some of the most regular, boring food, and it becomes hard to tell whether he was telling the truth. Perhaps, rather than detailing what he ate, he just said the first foods he could think of, like the time he said his hobbies include making cardboard models of London buses.

Anyway, for one week, I’ll be eating like Mr de Pfeffel Johnson, downing litres of Diet Coke, swilling cheap red wine and necking as many sausages as humanly possible to get inside, his brain. First, I had to prepare. I milled around Sainsbury’s hunting for everything on my list: sausages, Diet Coke, wine, tuna, lettuce and cake.

I spent ages looking for the cheapest wines they had because as Boris says, “it doesn't matter if it's expensive or not because all wine is good." So I picked up two bottles of £5 wine and headed to the checkouts. The man at the till saw the three litres of Diet Coke and bottles of wine in my trolley and asked if I was having a party. I had to say yes, because it was much easier than explaining what I was really up to.

DAY ONE

BREAKFAST: A slice of (birthday) cake and a latte.

SNACK: Three pain au chocolats and several cups of tea.

DINNER: Tuna and lettuce leaves.

Everyone in the office kitchen is impressed that I’m eating cake. But I can confirm that what your mother said is true – having cake for breakfast will make you feel sick at 9.30 in the morning, idiot. I’m also concerned by how hard it is to drink a whole litre of Diet Coke. Only nine hours in and I’m very ready to give up. I don’t actually want to talk about the tuna/lettuce dinner. Boris justifies it by saying: “I do think it's sensible not to have much dinner because then you have a brilliant incentive to get out of bed the next morning. There is such a feeling of optimism as you realise you can draw back the covers and eat; it's fantastic. A few lettuce leaves with tuna is enough.” What truly awful 'logic.'

DAY TWO

BREAKFAST: Toasted bagels with ‘I Can’t Believe It’s Not Butter!’ and marmalade.

SNACK: Three lattes.

DINNER: Bangers, mash and gravy.

I had to make instant mash for dinner because I got home at 9PM and if you think I’d start mashed potatoes then from scratch, you’re mistaken. That’s on me. I’m not sure whether it’s supposed to look so boring, but anything is better than tuna and lettuce, isn’t it.

Is it supposed to look like this?

DAY THREE

BREAKFAST: More leftover cake.

SNACK: A single pain au chocolat and some Diet Coke.

DINNER: Ribs and mash and a glass of white wine.

The wine is not bad at all. It was £5, so maybe Boris is right and price point doesn’t matter at all.

DAY FOUR

BREAKFAST: More bagels and margarine.

SNACK: A cup of tea and one chocolate and hazelnut croissant.

DINNER: Tuna and lettuce.

This is definitely a “me” problem – there’s nothing wrong with pastries or tea – but I hate them both. It took me an hour to nibble my way through a croissant, which is pathetic.

DAY FIVE

BREAKFAST: The last of the cake.

DINNER: Bangers, mash, gravy and cheap red wine.

Another wretched slice of cake.

I’ve decided that sausage and mash is not nice enough to be categorised as anyone’s favourite food.