There’s some bits at Simonside, sort of a combination of the way-marked trails and local knowledge. If you’re doing Simonside you’re better off combining it with the Carriage Drive (north side of Rothbury) for a decent ride, again local knowledge is best to get the best bits out of both.
Thrunton is a few miles away, best to go there only as opposed to linking it with Rothbury, unless you’re an animal 🙄
As for the “hidden trails” at Thrunton, it’s only a rumour, don’t believe everything you read on here 😉
Of course, I’d love nothing better than to provide some local knowledge, BUT, having decided to sell my one and only bike and have a year solely dedicated to munching the tarmac miles, I’m afraid it won’t be me, sorry.