Heather James, who is now 78 years old, looked after Simon as a little boy along with his brothers. The X Factor star and music mogul was in her care for five years and the pair were incredibly close, with Heather still referring to Simon as 'my little boy'.
Simon, who still calls his former minder 'Nanny Heather' as he did as a boy, revealed his heartbreak after hearing from Heather's carer in the US following a rapid deterioration in her health.
Heather was diagnosed with dementia just over three years ago.
'We had a bond when she was my nanny, she's an incredible person' Simon revealed. 'It's heartbreaking she's going through this.'
'My mum and dad adored Heather. In later years we met up and would exchange cards and pictures,' Simon went on to say.
Simon Cowell and his brother Nicholas, who was also looked after by Nanny Heather
'My every memory of her as a child was she was the sweetest, most kind person you could ever meet,' he added.
Heather's carer Eric praised Simon Cowell after the celebrity music mogul got in touch with his former nanny upon hearing of her ill health.
'It was a fantastic gesture, really caring. He asked all about her health – he was really concerned,' Eric said according to The Sun.
'He was talking about when he was growing up and how Heather looked after him and his brothers.'
Apparently Heather enjoys watching TV shows such as Britain's Got Talent and The X Factor so that she can see her former charge on screen.
'She sees him on TV on Saturdays and says, "There's my boy",' confessed Eric.
Simon is now a father himself to his three-year-old son Eric, whom he welcomed in 2014 with his partner Lauren Silverman, and has taken an active role in Eric's upbringing ever since, making sure to take his son around the world with him for work and include him in his many different ventures.