Ruth in Hollow Tree

Taken by 10 year old me in 1964 on my new Kodak Instamatic.
This was "the hollow tree" (Is it still there?) behind Rayleigh Lodge and at the top of Brocksford Avenue.
Questions for Ancient Tree people - is this an oak? and my memory says this was still alive - is that possible?
also, do any of you know what would cause the hollowing out? and how ancient could this tree potentially be?
Thanks for any insights!