"1970, so quite a while before the film then. Too bad, might have made for some interesting interactions with the filmmakers"

Must have been some time about then. You can see him in front of that fence pointing to the void where it was.

I went back a few times over the years and it lay mostly as a gap site until I think the nineties or later.
Interesting name btw. Graham is a Scottish spelling of "Grim": a personal name but also a byword for Odin or the Devil.

The family of that name was a notorious border cattle raiding clan and the very name banished in Scotland...some returned under the name Ma'harg...
Graham backwards.

Strange to say I still occasionally dream of being an Otter or water creature in the water of Leith which flows nearby...a repetitive dream I've had since childhood. Don't ask me what that means...I have no idea!