The following is from the Sun Life website www.sunlife.co.uk/articles-guides/your-life/what-is-grandparents-day-and-when-is-it-in-the-uk/
“Originating in America, Grandparents’ Day became a recognised holiday in 1978 following Marian McQuade’s campaign to create a day to celebrate grandparents.
After volunteering in a nursing home, she discovered that many of the residents got little to no visitors. This inspired her to create a day that highlights the importance of the older generation to the younger generations.
On 3rd August 1978, President Jimmy Carter signed a proclamation saying that the day is intended “to honour grandparents, to give grandparents an opportunity to show love for their children's children, and to help children become aware of strength, information, and guidance older people can offer.”
Grandparents’ Day was first introduced in the UK in 1990 by Age Concern. Since October 2008, it’s been celebrated on the first Sunday of October every year.”
I find the rest of the page cringey, bordering on the patronising