Hi Jilly,
I'm pretty sure that they have passed on. I no longer live in that part of the world, but my friend, (who can usually be relied upon to know everyone), has only a vague recollection of them.
I visited the Brewers just once, to take a look at Sam's grafted "family" fruit trees, and that was probably 30-odd years ago.
Wellwick House has a huge amount of history, and ghost stories - It is very imposing, standing on a 'cross ridge' that comes down perpendicular to the Chiltern scarp. I didn't know the Urvines, I'm afraid, but I know that the house has links to Judge Jeffries, and it is currently owned by a nice couple from Ireland.
One other point is that, if, for instance, you were thinking of getting electoral roll extracts from the County archive, in Aylesbury, I seem to remember that the House sits right on the parish and district boundary, so it could be counted in Wendover or Ellesborough.
Good luck with it,
Timoth