Hever Castle was built in the 13th century and later converted into a manor house by Geoffrey Boleyn in 1462. His son Thomas inherited the castle in 1505 and lived there with his wife Lady Elizabeth Howard and their children George, Mary and Anne, who was later to be Henry VIII's second wife. Upon Thomas' death in 1539, Hever became a crown property of Henry VIII and was bestowed to Anne of Cleves as part of her divorce settlement in 1540.
Passing through three further owners, in 1903 the fabulously wealthy American William Waldorf Astor became the castle's new custodian. More recently the castle was purchased in 1983 by the Guthrie family, who are its current owners.
Recording in any location when it's open to the public in my opinion invalidates potential EVP captures. It's impossible to be certain of conversations around you, so accessing a site out of hours is imperative. Fortunately I was able to stay at Hever Castle for a few days, and as a guest I could enter when there were very few people present, albeit for a very limited time. I am confident that recordings I have proposed as EVP are not mutations of speech from those in the building or of guests outside.
The quality and quantity of clear voices I captured at Hever Castle were remarkable, it was by far the most productive solitary visit I've ever made. I would thoroughly recommend visiting if you can, history really does feel alive when you wander its rooms and gardens.