Where is his VC? If it's on display it may be with that. Annoyingly many of the original citations appear to be missing along with the witness accounts. The National Archives only has a fraction of the 182 WW2 VC citations. I'm wondering if a typed version of the original is in ATB's D-Day as I recall they do a few pages on his VC including an interview with him. Have you tried the Green Cowards museum?
I haven't tried anywhere else yet, this was the first port of call. Unfortunately Google doesn't always have the answers. I will have to search further.
Browsing this interesting thread, and remembering the wiki entry here: https://en.wikipedia.org/wiki/Stanley_Hollis#Legacy Which seems to have an answer to what happened to his VC: "His Victoria Cross was bought by medal collector Sir Ernest Harrison OBE, chairman of Racal and Vodafone. Harrison presented the medal to the Green Howards Museum in Richmond, North Yorkshire in 1997. Ten years later, he purchased, for the Green Howards, the Normandy hut which Hollis had attacked." Hopefully this is one of those rare times where wiki is 100% correct Re. the "Lavatory Pan Villa" though, it was such a strange name I had to look it up Seen a few links which say in effect: "they call “Lavatory Pan Villa” because of the shape of the drive way in aerial images." i.e. http://www.iwm.org.uk/collections/item/object/205021921 "Overhead aerial of the gun battery at Mont Fleury, behind 'King Red' Beach GOLD Area, after air bombardment, showing four medium casemates under construction. Note also the anti-tank ditch, (right), and minefields, (centre top). The battery consisted of four 12.2 cm Polish guns (one in a completed casemate) manned by elements of the German 1260th GHQ Coastal Artillery Battalion, and was captured on 6 June 1944 by 6th Battalion, The Green Howards." There's also some worthwhile and really interesting* details here: (*It's Osprey - so of course!) D-Day 1944 - By Ken Ford, Howard Gerrard https://books.google.co.uk/books?id=f2uucTfnvEwC&pg=PA45&lpg=PA45&dq=Lavatory+Pan+Villa&source=bl&ots=p80UMbk6H2&sig=ERkCu344D_1DZAaA4Zm7645S8CM&hl=en&sa=X&ved=0ahUKEwjKjqz5uq7KAhXKWhoKHTeADsMQ6AEINzAF#v=onepage&q=Lavatory%20Pan%20Villa&f=false All the best, Rm.
Stanley Elton Hollis in the UK, Victoria Cross Medals, 1857-2007 Name: Stanley Elton Hollis Birth Date: 21 Sep 1912 Birth Place: Middlesbrough, Yorkshire Birth Place Modern: Cleveland Death Date: 8 Feb 1972 Death Place: Liverton Mines, Near Loftus, Cleveland TD
The Green Howard museum also has a recording and a transcript of a talk given by Hollis on one of the Staff College battlefield tours to Normandy. This is also included some of the anthologies about D Day.