British cycling star Mark Cavendish and his wife were subjected to a knifepoint robbery while at home with their children, with one masked raider threatening to stab the athlete, a court heard on Tuesday.

The intruders made off with two Richard Mille watches, valued at a combined £700,000 ($839,000) from the property, about 25 miles northeast of London, in the early hours of November 27, 2021, the court was told.

Cavendish jointly owns the record for stage wins at the Tour de France, with 34 victories to his name, and also won an Olympic silver on the track at the 2016 Rio Games.

The 37-year-old and his wife Peta were in bed with one of their young children when they were awoken by noise, said Edward Renvoize, opening the prosecution case at Chelmsford Crown Court.

One intruder "produced a knife and threatened to stab him up in front of his children," he said. "At this point there were three in the room and they began asking where the watches were."

Renvoize said two watches were taken, one valued at £400,000 and the other at £300,000.

Renvoize said Peta Cavendish's phone was found outside the property, and that the "misplacing of that telephone by one of the robbers" was an "error in what was a carefully planned and executed robbery".

He said forensic examination of the phone led to the discovery of DNA attributed to 28-year-old Ali Sesay, of east London, who had "pleaded guilty to the offence of robbery already".

Renvoize said police "were able to identify a number of other individuals who appeared to have been in communication with a telephone belonging to Mr Sesay".

Romario Henry, 31, and 28-year-old Oludewa Okorosobo, who live in London, both deny two counts of robbery and are on trial.

They are accused of robbing Cavendish of a watch, phone and safe, and of robbing the athlete's wife, described as a "successful model and media personality" of a watch, phone and suitcase.

Prosecutor Renvoize said the "robbers were armed with large knives", "had concealed their identity with balaclavas" and "meted out violence to Mark Cavendish".

"It's quite clear the assailants were interested in obtaining watches and once they got the watches they left the premises with very little else," he added.

The trial is estimated to last around two weeks.