Hi.
I was at the Leavesden Hospital Burial Ground a couple of days ago. It's down the now very neglected East Lane. Here's a 'tinyurl' link to the location on Google Maps:
http://tinyurl.com/yjr8ow8It's the wooded square where the road bends 90 degrees.
It's a sad and very neglected spot, and whilst the findings of the report posted above imply that it's beyond tidying up. I don't think it is - I was able to roam freely without encountering impenetrable undergrowth. I think the council don't really want to get involved. I have no faith, but respect the memory of the dead, and think it's a shame that those who were largely forgotten and neglected in life continue to be so in death!
Out of curiosity I examined several of the gravestones, but can't recall seeing a 'Vaughan', but a more thorough search may be rewarded. It's unlikely that I'll visit the place again - the lane is virtually impassable to traffic (I was walking when I went), but if I do I'll check for your ancestor and report back.
There's a plaque stating that the records are in the chapel at Leavesden Hospital - but the chapel is now used for business purposes! It may well be that the book is now with a local church.
I took a photograph of the lych gate at the entrance.
Jim