The beautiful daughter of powerful Greek shipowners who recently beat cancer has died from an insect bite after visiting two different London hospitals and at the end being sent home.

Marissa Laimou (also Lemos), was found lifeless in her bed by her housekeeper at the apartment where she lived in London on 11th September.

Greek media reported that Marissa began to feel unwell on 8th September when she developed dizziness, itching, fever and other signs of infection.

Marissa Laimos poses in undated photo with her mum. She was found dead in her apartment in London, UK. Note: Private photo. (Newsflash/NX)

A doctor who visited her at home prescribed paracetamol but her condition did not improve.

She then went to a London hospital and also saw her oncologist, who arranged for her to be sent to another hospital by ambulance.

But family and friends said nurses, rather than doctors, examined her and concluded she did not need to be admitted.

She was discharged in the early evening with antibiotics and a diagnosis that referred to an insect bite.

The following day she was found dead in her bed.

Marissa Laimos poses in undated photo. She was found dead in her apartment in London, UK. Note: Private photo taken from social media. (Newsflash/NX)

Her mother, Bessy, told Greek media that toxic shock caused by an insect bite killed her, although it is currently unclear which type of insect bit her.

She said: "My daughter had survived cancer and died from an insect."

She added: "She was a girl with so many gifts, all of England is crying, all her doctors too…"

Relatives said the autopsy had not yet been carried out and would take about a week.

The hospital involved has reportedly admitted that a serious mistake was made and has opened an internal investigation.

Her aunt said the family would have no answers until the post mortem is completed.

Picture shows Bessis and Diamantis Laimos with their children, undated. Marissa Laimos was found dead in her apartment in London, UK. Note: Private photo. (Newsflash/NX)

Friends said Marissa had recently staged a production of Romeo and Juliet in London and was preparing another theatre project.

They described her as talented, modest and devoted to the arts after surviving breast cancer.

She had previously worked in Paris with designers Sonia Rykiel and John Galliano before founding Rainbow Wave, a company that introduced international brands to London stores.

Marissa Laimos poses with her mother Bessy Laimos in undated photo. She was found dead in her apartment in London, UK. Note: Private photo. (Newsflash/NX)

The Laimos family are one of the best known names in Greek shipping, with business roots stretching back to the early 20th century.

They are now mourning the death of their daughter, whose life bridged the worlds of high society, fashion and theatre in the British capital.