Simon – who is also a former presenter of BBC children’s show Blue Peter – took to Twitter to announce the heartbreaking news, stating he was 'crushed with indescribable pain' following 40 year old Gemma’s sudden death.
Today I am crushed with indescribable pain. Just three days after falling ill with Acute Myloid Leukaemia, my dear wife Gemma passed away yesterday evening surrounded by her family and friends.
'If you are a prayer - pray for my boy Ethan. 8yrs, precious and in bits. Thank you,’ the 44-year-old wrote.
Acute myeloid leukaemia is an aggressive and rare form of blood cancer, with symptoms usually developing over a few weeks and quickly becoming more severe.
According to statistics, only 2,6000 people in Britain are affected each year.
Speaking to The Mirror, Simon explained that Gemma started feeling unwell last weekend and went to the doctor three times before finally being admitted to hospital.
Sufferers of AML often complain of pale skin, tiredness, breathlessness and constant infections.
Describing his son’s devastation, Simon explained, 'He said he wants Playmobil and other gifts for Christmas, but most of all "I want mummy back", and I can't help him with that.'
Following tests, Gemma begun chemotherapy on Tuesday night, however it was too late to save her.
'For the first couple of days she was responding well, but yesterday morning she went downhill very quickly. She had bleeding on the brain. I was told yesterday morning she would be gone in a few hours.'