It was part of a plot by two serving Coldstream Guards officers to sell him ammunition, prosecutors allege.

Southwark Crown Court heard the police officer also visited Kirtland Gill's house to collect a batch of bullets.

Mr Gill, 41, denies conspiracy to sell ammunition and possession of a prohibited weapon. Rajon Graham, 33, previously admitted selling ammunition.

At the time of the alleged offences - between December 2020 and January 2021 - Mr Gill was serving with the Coldstream Guards - part of the Household Division, which is responsible for the protection of the Queen and guarding Buckingham Palace and Windsor Castle.

The court has heard how Graham sold a total of 300 9mm Parabellum bulleted cartridges, which he called "sweets", to the police officer, referred to as "D".

The bullets were wrapped in Bacofoil bags, and sold for £5,800 in cash across four meetings with "D", the jury was told.

'Nervous on camp'

The court heard Graham had taken "D" to Victoria Barracks, near Windsor Castle, where the regiment, known for its red jackets and black bearskin hats, is based, on 17 December 2021.

Giving evidence from behind a screen, the officer said: "When we entered the camp, he had obviously spoken to the guards at that point.

"I was nervous of being on a military camp in the way I was portraying myself as a criminal."

"D" said they parked on the parade square, while waiting for Graham's friend, who he said was being interviewed by The Sun newspaper.

The court has heard Mr Gill was interviewed because he was the first black regimental sergeant major in the Household Division.

The undercover officer told jurors he said to Graham, who he knew as "Solj", that he thought it was "too risky" for him to be on the base.

'Did not enter armoury'

"He kept saying it was fine, I was with him and while I was with him everything would be okay," "D" said.

But asked by prosecutor Duncan Atkinson QC if he took Graham up on an offer to view rifles in the armoury, D said: "No. I decided that was a bad idea.

"It was a challenge to go into the Army base, but to go into the armoury with live weapons with whom I perceived to be a serious criminal was not a risk I was willing to take."

Graham is then said to have driven "D" to Mr Gill's nearby home to collect a batch of ammunition, which he bought for £1,000.

The trial continues.