A former Queenstown horse trainer is accused of killing her ex-boyfriend in Britain and watching his body burn on a garden bonfire while she drank red wine with a friend.

Kirsti Windsor, 38, had worked at Queenstown's Moonlight Stables for more than a year before moving back to England in early 2008 with her then boyfriend, landscape gardener David Langdon, 40.

Windsor is charged with killing him between August 9 and 12, 2008 and perverting the course of justice.

Moonlight Stables owner Geoff Clear told Queenstown's Mountain Scene newspaper he was dumbfounded Windsor was facing murder charges.

"Like any other couple they had their ups and downs, but never in a thousand years would I have thought Kirsti could be capable of something like that, or that David deserved anything like that."

Mr Langdon also worked part-time at the same stables.

"She always came across as a kind person and a dedicated worker who didn't appear to have a mean bone in her body," Mr Clear said.

"Kirsti was last in touch with us a few months ago while she was still on bail and insists she has done nothing wrong."

Windsor allegedly murdered Mr Langdon when he refused to move out of the remote cottage in Wormelow, Herefordshire they shared since February 2008, the Telegraph reported.

Worcester Crown Court heard the couple had ended their four-year relationship after a series of violent fights.

Windsor ordered Mr Langdon to leave the house when he tried to strangle her. She then went away for the weekend, but when she returned he was still there, the court heard.

His remains were found three days later when Windsor called police and said she believed Mr Langdon had committed suicide.

He was so badly burned that a cause of death has yet to be established.

Prosecutor Christopher Millington, QC, told the jury it was completely inconceivable that Mr Langdon would do that to himself.

"Only two people know what happened to Mr Langdon at the cottage, one of them is dead and the other is Miss Windsor. "Unhappily for Miss Windsor, it proved more difficult to incinerate a human body outdoors than she realised."

He said Windsor enlisted the help of her friend Katie Brown, 31, to help dispose the body, and the two had sat on the patio drinking wine. A large bonfire in the garden was allegedly seen and smelt by neighbours.

Windsor and Brown deny a charge of perverting the course of justice by attempting to destroy the body.

The trial is expected to last seven weeks.