Clarification on private residential property

I had a submission come up for a beautiful old country house that used to also be a castle, but wasn’t sure how best to review it.
The issue that I had is that it appears to be private property, however the owners hold ‘open days’ to allow people to explore the grounds, and they accept private bookings for wedding photos and things.
My feeling is that because they sometimes open up to the public, then it could be considered eligible, but is this correct?
I appreciate any feedback people have :)
Comments
It is whether the POI is in single-family residential property or not.
If it is, it still meets eligibility criteria but also a rejection criterion. Still a PRP rejection.
Rejection reasons override acceptance reasons. It can have historic relevance and public access and still be PRP, and therefore ineligible.
Thanks for the insight, very helpful!