Archie Lyndhurst died from a brain haemorrhage as a result of a rare form of leukaemia, his mother Lucy Lyndhurst has revealed.
The 19-year-old actor - son of Only Fools and Horses star Nicholas Lyndhurst - died suddenly in September at the family home in London but the cause of his death was not immediately apparent.
Taking to Instagram, Lucy revealed that the results of her son's post-mortem came through just before Christmas and identified the underlying cause as a very rare, rapidly-moving form of cancer.
"Four days before Christmas Nick and I sat in Harley Street with the results of Archie's second post mortem," she wrote. "A very detailed document, which we had been warned by the coroner would be a harrowing read, and best explained by a medical practitioner.
"The Dr explained Archie died from natural causes (something we knew already, only gossips, keyboard warriors, trolls and the ignorant thought differently)
"He died from an Intracerebral Haemorrhage caused by Acute Lymphoblastic Lymphoma/Leukaemia. This is not Leukaemia as we know it, the word Acute in medical terms means rapid.
"He assured us that there wasn't anything anyone could have done as Archie showed no signs of illness. Archie had numerous bleeds on the brain and the Dr went to great lengths to reassure us that he wouldn't have been in any pain as it happened in his sleep.
"The results utterly floored us to think something like this could happen. It's very rare and around only 800 people a year die from it."
She continued: "Archie was an empath. He loved life, he valued everyone in it and every moment he was given. He was always singing, and had such energy and passion in everything he did.
"To be part of his life has been the biggest joy mad honour. We miss him everyday and always will. There aren't enough words to describe him, he was a one off, and beyond unique."