Top barn or bottom barn ??
As a local I've never noticed if it's way marked or not.
If you walk behind the top barn and follow the track UP you'll come out at a car park and have the choice of 2 routes.
The track on the left is direct and steep, the one on the left is more gradual and goes through the Japanese gardens.
Enjoy.
PS if the weather is ok it will be really busy so just a matter of following the crowd.
PPS I asked Mrs Rivington and she said it is signposted but also mentioned parking as it gets full, early doors near the 2 barns.