Sharing the heartbreaking news on Instagram, Holly wrote: "Sleep well Sandra… Nonna, Mother, Sister, friend… To know her was to know strength itself… Raising four children after losing her husband, she then lost a son and more recently her sister…
"Thank you for your guidance, advice and bottomless Prosecco. Thank you for raising the incredible man I’m married to… I see your strength everyday in our children… Be at peace…Love you."
A number of stars shared their condolences including host Vanessa Feltz, she said: "I am so terribly sorry to hear of Sandra’s passing. I had such a memorable conversation with her. She exuded wisdom, kindness and warmth. Sending love to you Dan and the whole family."
Dr Scott Miller wrote: "So sorry lovely friend. I lost my amazing mother-in-law recently who I miss every day, so I can appreciate the pain you’re going through. Big love to you and D."
Holly has faced a number of tough times over the last 12 months, including a public backlash after she was photographed visiting our late queen without queuing. The presenter insisted she had been there to film for a segment of the show which is why they used the VIP lane.
Then last month, public pressure increased again after it was revealed her former cohost Phillip Schofield had had an affair for an ITV crew member. It's understood that Holly and Phil won't be holidaying together this year, which is something that has become a tradition for the two families.