Lower Trethinna Cottage is in Trewen, which is a small hamlet just off the A30 in mid-Cornwall. It's a detached stone cottage. It's old. It's Grade II listed.
It sleeps four. Two bedrooms and one bathroom. The rating is 4 Star, which reflects that it's been modernised where it matters. The kitchen and bathroom are good. It's got a wood burner in the living room, which works well. The floors are original slate in some rooms and there are a lot of old beams. The ceilings are low in places. You'll know you're in an old cottage.
The stairs are mentioned in the official note for a reason. They're steep and a bit narrow. They're cottage stairs. Not a problem if you're steady on your feet, but something to be aware of.
Outside, there are a couple of small patio areas with benches and an enclosed garden. You can park one car right at the front of the cottage.
The location is good for getting around. You're on the A30 in a few minutes, so you can get to either coast or up onto Bodmin Moor fairly easily. The nearest shop and pub are about three miles away in St Clether. Port Isaac is about a 25 minute drive if you want that classic Cornwall harbour. Tintagel is a bit further, maybe 35 minutes.
Facilities are all there: WiFi, TV, washing machine, dishwasher, a cot and highchair if you need them. Bedding and towels are included. You can bring one well-behaved dog.
For planning days out, the National Trust Cornwall site is useful, and Cornwall Area of Outstanding Natural Beauty has good information.