A firefighter has described how an alleged killer calmly shrugged off the discovery of a French nanny’s charred remains in his garden as if to say “the game’s up – I’ve been caught”.

Sophie Lionnet, 21, was allegedly tortured and killed by her employers and then thrown on to a bonfire at their home in Wimbledon, south-west London.

Neighbours alerted the fire brigade after noticing smoke and a “horrible” smell coming from the property on the afternoon of September 20 last year.

Sabrina Kouider, 35, and Ouissem Medouni, 40, have admitted perverting the course of justice by attempting to burn the body but deny murder.

Firefighter Thomas Hunt confronted Medouni after he found human fingers and a nose as he put out the fire, the Old Bailey heard.

The bonfire was near a barbecue with chicken cooking on it.

Giving evidence, Mr Hunt said: “I thought it was a very strange place for a self-started bonfire because of the close proximity to the tenants’ or owners’ property.

“The pile of debris caused damage to the property.

“I thought ‘Why has he done that here?’ I spoke to the tenant and said ‘Why would you do that?’.

“He just shrugged his shoulders.”

Mr Hunt told jurors he used a small amount of water to put the fire out and was turning it over with a spade when he saw what appeared to be “two blackened logs”.

He also noticed clothes and jewellery among the ashes, he said.

He said: “When I recognised it was a body I was concerned for my crew’s safety so held it to myself for what seemed like 20 seconds because I did not know if I challenged the occupant what might happen next.

“We were very close to leaving, our job was done. At that point I called to my colleague Jo ‘ That’s a body’.

“I turned to the occupant and asked ‘Why are you burning a body?”

“He said ‘It’s a sheep’.

Mr Hunt said “Bollocks” in reply.

He added: “I quickly ran through features of a body found on a human being. I could make out a nose and fingers just to get confirmation from my colleagues it was what I thought it was.”

Asked how Medouni seemed, he said: “Very calm. When I challenged him he shrugged off the accusation.

“When he sat down there was a look of resignation on him, like ‘The game’s up, I’ve been caught’.”

In cross-examination, Orlando Pownall QC suggested Medouni may have been “in a daze”.

Another firefighter, Joseph Wood, said: “It looked like a body because of the way it was lying. I could see a nose. Then I saw tissue and bones and then a hand with five fingers and was certain it was a body. It also started to smell like a body.”

The officer said Medouni repeatedly told him it was “a sheep” he had got from Wimbledon market.

He said in a statement read to court: “As soon as I saw the nose on the body, I called for police assistance as a body was being burned.”

Neighbour Nancy Nathanson told jurors she never liked the defendants because they were “anti-social” and “odd”.

She said Kouider “always looked glamorous, with nice clothes, big sunglasses”, but Medouni’s French car would get parking tickets and their rubbish was left out.

She told jurors: “It seemed they had a very anti-social way of existing.

“When you live closely with people and they are inconsiderate, it affects you. I know the man who rented the house and they did not pay their rent.

“It was very odd the way they operated. It was very unusual.”

Jurors have been told that “shy” Miss Lionnet’s last words were recorded in a so-called video-taped confession on September 18.

The defendants allegedly beat and interrogated her for hours over a false accusation that she was in league with Kouider’s ex-boyfriend, Mark Walton, a founding member of the band Boyzone.

In the harrowing final footage, she appeared emaciated and broken.