I've just found this thread. I'm a related Espinasse. It's fascinating to learn more about the brewery. Family legend always had it that we owned the site at the time Guinness bought it, but I think my mother found out the true story, back in the '80s-90s(?) and put us straight! I believe there's an Espinasse chair (and maybe a portrait?) in the current brewery, which I don't really see the relevance of if there's no real connection. Maybe we should ask for it back!
My mother and sister visited Dublin to try to understand the estate. I think there is still some property there, on 999-year leases for tuppence a year (maybe it was 9,000 years is that's the term of the brewery site?). I seem to recall that they were warned off – politics and fear of reprisals. They couldn't really find anyone to help them, and the enquiries they were able to make discovered the records are 'unavailable', so no one knows who holds them or who's been collecting the rent!
They did go and look at Kill of the Grange though. I understand that that's the name of an area, but there was a family house. Is that the one now listed as Fairholme? The boar in the mosaic floor would suggest that it is. The family crest is a boar with an arrow through its head.