I'm a granny (I'm 55) to a nearly 2 year old.
I love it.
I dropped to supply only at work so that I could do child care and have him 2-3 long days a week as my DD and her dh are nurses so they often need care til very late so I get to put him to bed.
I do soft play, trampolining, toddler groups. We plant and dig the garden, we read endless stories as he already loves books, we bash on my piano ( it pains me a little but I want him to want to play!) We get filthy and messy and we have fun.
My DD and me are so similar in outlook that it's been very easy to be his Granny, and I work with children so it feels natural. I send pics of his days with me, and always feedback how the day has gone.
I don't give advice unless asked, but my DD is parenting him pretty much the same way I did her, and they are fabulous parents and he's a dear little boy so we are harmonious :)
I feel lucky that they live close by and I am able to help out, because it's a privilege to be entrusted with him.
I genuinely don't understand those who say 'I've done my bit, not helping'
I knew I'd love any grandchildren, but I was absolutely staggered by the overwhelming love I felt when he arrived.. child of my child. It is a very special relationship.