A neo-Nazi teenager was snared by MI5 as he attempted to buy a gun for a terrorist attack, a court has heard.

Alfie Coleman was aged 19 when armed police swooped to arrest him outside a Morrisons supermarket in Stratford, east London, on September 29 2023.

Lunchtime shoppers bore witness to the “shocking scene” when three men pointed stun guns as Coleman as he walked across the car park carrying a bag, jurors heard on Wednesday.

Nicholas De La Poer KC said the bag contained what appeared to be a handgun and around 200 rounds of ammunition.

Counter-terrorism officers knew what he was carrying because “they had sold them to him”, the prosecutor said.

The arrest was the culmination of “persistent” efforts by Coleman to get hold of a gun, including contacting people online, the Old Bailey was told.

Mr De La Poer told jurors: “Unbeknownst to him, Mr Coleman had been talking to several undercover operatives over the previous months, as he sought to purchase a firearm via encrypted messaging platforms.

“This had culminated in MI5 undercover operatives agreeing to sell a firearm and the bullets to Mr Coleman. The arrangement made was for the supply of a Makarov pistol, five magazines and 200 rounds of ammunition.

“Mr Coleman was told these items would be in a Land Rover Discovery parked in the Morrisons car park. He left £3,500 in cash in the front passenger seat footwell and collected the bag containing the items from the boot.

“Before he had gone 30 yards, Mr Coleman was confronted by armed officers and he was arrested.”

The prosecutor said Coleman harboured an extreme right-wing ideology and was planning to use the gun in a terrorist attack.

He “idolised” the likes of Thomas Mair, who murdered MP Jo Cox, and believed in white supremacy and neo-Nazism, the court was told.

He collected a number of terrorist documents, carried out online research and wrote a manifesto, it was alleged.

Mr De La Poer said: “The prosecution’s case is that Mr Coleman engaged in conversation on encrypted social media platforms such as Wire and Telegram with people whom he thought were sympathetic to his views.

“And it was through such people that Mr Coleman sought to buy a firearm. A mission which led him to the Morrisons car park in Stratford on the morning of September 29.”

The court was told of an alleged earlier first attempt at writing down an attack plan dating back to June 2022, a week before he turned 18.

In it, Coleman allegedly identified his target as the “Mayor of London house” and included the postcode for the Lord Mayor’s residence, jurors heard.

In a section headed “weapons I can get easy”, he allegedly listed “knives” and “crossbows”, the court heard.

In September 2022, Coleman allegedly wrote a list on his phone with offensive language next to a number of vehicle number plates.

Jurors were told Coleman was working at Tesco at the time and however he presented himself at work was “seething with hatred on the inside”.

Mr De La Poer said the phrase “race traitor” was written beside some of the number plates, including that of a white female co-worker.

The court heard Coleman had pleaded guilty to possession of 10 documents useful to terrorists, attempting to possess both a firearm – which had been deactivated – and ammunition.

Coleman, now aged 21, of Great Notley in Essex, has denied preparing acts of terrorism.

The Old Bailey trial continues.