Sophie Winkleman, pictured left– who is married to Lord Frederick Windsor – faces weeks of recuperation after suffering a suspected broken back and broken foot, according to a source close to her family

Claudia Winkleman’s half-sister – actress Sophie Winkleman – has been seriously injured in a head-on car crash while being driven home from a film set.

The 37-year-old – who is married to Lord Frederick Windsor – faces weeks of recuperation after suffering a suspected broken back and broken foot, according to a source close to her family.

The mother of two was sitting in the back seat of the chauffeur-driven car when the accident happened. It is believed another vehicle swerved to avoid a deer in the road and ploughed into her car – injuring her and both drivers.

According to witnesses, the first emergency personnel on the scene saw the horrifically mangled wreckage and feared Ms Winkleman was more gravely injured.

Five ambulance crews, including an air ambulance, were dispatched to the crash near Saffron Walden, Essex.

She was initially rushed to Addenbrooke’s Hospital, Cambridge, along with the drivers of both vehicles, before being transferred to London’s Chelsea and Westminster Hospital.

She was on her way home from filming Trust, a major new American TV series for Slumdog Millionaire director Danny Boyle at nearby stately home Audley End House when the accident happened ten days ago.

The actress is still in hospital and has been visited by members of her family, including her father-in-law, the Queen’s cousin Prince Michael of Kent.

The source added: ‘It was a terrible shock for the whole family. Freddie’s looking after their two girls while Sophie recovers. It will be a long road for her, but we’re all so thankful that she’s been told there won’t be any long-term problems.’

Ms Winkleman and Strictly Come Dancing presenter Claudia, pictured with fellow host Tess Daly, share a father in retired publishing executive Barry Winkleman, 78

Picture shows actress Sophie Winkleman on the set of the new TV series called Trust being filmed near near Saffron Walden, Essex

It was not clear last night whether the accident might force a postponement in the filming schedule for Trust, which stars Hollywood veteran Donald Sutherland and Oscar-winner Hilary Swank.

It tells the story of the kidnap of oil company heir John Paul Getty III, and is due to air on cable channel FX early next year.

Ms Winkleman, who still uses her maiden name professionally but is formally titled Lady Frederick Windsor, has enjoyed a successful acting career including a part in hit US sitcom Two And A Half Men, playing the girlfriend of Ashton Kutcher’s character.

She married financial analyst Freddie Windsor, 38, in a lavish ceremony at Hampton Court Palace in 2009.

The Strictly Come Dancing presenter's sibling, Sophie Winkleman, 37, suffered a suspected broken back and foot after the vehicle she was in crashed into a car that swerved to avoid a deer (pictured far left and far right in June)

Yesterday, a skid warning sign had been placed at the crash scene

The couple’s elder daughter, Maud, is a four-year-old reception class contemporary of Prince George at Thomas’s Battersea, South London.

Her sister, Isabella, was born last year. Ms Winkleman and Strictly Come Dancing presenter Claudia share a father in retired publishing executive Barry Winkleman, 78. Sophie’s mother is children’s author Cindy Black, while Claudia’s is former newspaper editor Eve Pollard, 71.

Yesterday, a skid warning sign had been placed at the crash scene. Ms Winkleman’s agent Kirk Whelan-Foran did not return our calls. A spokesman for FX could not be reached.