The tensions of gentrification have created an unlikely flashpoint in the hipster heartland of east London. On one side is a cereal-selling, silver-haired hipster named Gary Keery. In the other is Symeon Brown, a Channel 4 news reporter, in an “overpriced River Island suit”. The location: Cereal Killer – a Shoreditch cafe that opened last week, set up by Keery and his identical twin, Alan. It sells 120 varieties of cereal and 13 types of milk.

The idea for the cafe was born out of a hangover, when the Belfast-born twins craved a breakfast cereal. Battle began when Channel 4’s Brown asked Keery a series of questions relating to the bowls of cereal, which have a minimum price tag of £2.50.

Brown, who didn’t sound too pleased with his cereal and strawberry milk, said: “Do you think it’s affordable for the area?”

“I think it’s cheap for the area, really,” responded Keery.

Brown continued: “Do you think local people will be able to afford £3.20 cereal?”

Keery: “If they’re poor, probably not then. Can we stop this interview because I don’t like the questions you’re asking me?”

The encounter lasted less than a minute, but went viral and hipster-bashers across the country briefly turned on Keery and his cereal cocktail, Chocopotomus. Some commentators defended him, others lashed out for failing to acknowledge the extreme poverty of Tower Hamlets.

This weekend the bearded entrepreneur got in the knockout blow in an open letter to Brown and Channel 4 sent via the Cereal Killer’s official Twitter account. And now he has a queue of cereal enthusiasts outside his shop.

In the letter Keery insisted that, once his business had its feet on the ground, he would be helping charities to provide breakfasts for underprivileged children in the area.

“You obviously don’t understand business if you think I don’t have to put a mark-up on what I sell. It may be the poorest borough in London, but let’s not forget Canary Wharf is also in the borough – but I am the one to blame, eh?” said Keery.

He continued: “I am from one of the most deprived areas in Belfast, so me and my family know all about poverty but haven’t had to blame the small business owners in the area for it. I have been taught a great work ethic and have made it this far without blaming small business owners trying to better themselves and make a future for themselves.

“I still have to pay over-the-top rent for my premises and pay the 12 staff I have employed, so I either have to make a profit or I will be out of business. Maybe if I charged more than £3 for a coffee and dodged all the taxes in this country like some cafes – the reporters would leave me alone, would they?

“If you want someone to solve the poverty crises in London, I don’t think I’m the man to do that as I am too busy trying to cure Ebola and get Kim Kardashian to keep her clothes on,” the open letter added. “Also you didn’t even pay me for the cereal, which you could so easily afford with your overpriced River Island suit, so I will send you a bill for the extortionate £3.20.”

The letter ended: “Yours Sincerely, Gary Keery (the worst person in the world).”

On Saturday Keery – speaking briefly before rushing back to an increasingly manic crowd – confirmed he had received no apology or comment from Channel 4.

Channel 4 declined to comment.