I think the fact that there are two different ads on rightmove could be working against you. The two listing are so different from one another that when browsing I initially thought they were two different houses and was comparing them, then realised they were one and the same. This would seriously put me off as it makes me wonder what is being hidden as clearly neither is fully trustworthy.
There are very few properties of this size on the market in this area - even with a search radius of 9 miles there's only a handful and your place is certainly the cheapest.
So who will your buyers be? They are unlikely to be people looking specifically for something in Tarset. More likely they will be looking all over Northumberland for the right combination of features.
Your ad needs to do more to address immediate concerns. How far is it to the nearest shop, pub & cashpoint? Where are the bus routes? What is great about living right here rather than the many other equally charming spots in Northumberland?
Additional concerns fir parents: Rightmove shows the nearest primary school is 2 miles away and is only 34 pupils only going up to age 9. Senior schools are 17 miles away and start from age 13 - where do 10-12yo kids go? What is school transport like?
The stable facilities are barely mentioned - do more with this. If a rider is interested then they will want to know about the local bridle paths and how safe the nearby roads are for horses.