As The People's Friend make their guidelines available online, I'm just giving you the link, rather than copying them here - that way you'll have the most up to date version, whenever you look.
The fiction editor also has a blog. If you want to write for this market, I suggest you follow that as there are often hints about what they're currently looking for, clues about why they've accepted certain stories and even warnings about subjects they've had enough of.
This magazine has been going a long time and although it hasn't changed drastically it has changed. If the copies you're relying on for research are a few years, or even decades, out of date get yourself down the newsagent's. That goes for all the magazines, but it's with this one in particular that people seem to assume they know what it's like without having read a recent copy.
In case you're wondering, the castle is Threave - it's in Scotland and it has changed a bit over the years, yet would still be recognisable to those who once lived there.