I was searching the net and up came Revells Hall, surprise surprise. I used to play there when I was a child, thats a long time ago.Around 1950At that time used to be owned by a family called Savory, genteleman farmer had a high class pedigree herd of Jerey cows. Not that that has anything to do with the Grevilles.
I have some photos of the place if you are interested, I took them whilst on a visit a few years ago, reliving old times.
By the way the actual place is at Bengeo, Hertford, not Hoddesdon. If you like I can give more info on Google Maps (I think)