Edward Heath lived at Arundells, in the Cathedral Close in Salisbury. When there was talk of closing it to the public due to cost (it has now been reprieved for the moment), I wrote to the NT asking if they would consider buying it, as a former PM's house and grounds would make a good addition to their properties. I had a very long reply, part of which I include in this post.
The National Trust’s acquisition process is very rigorous. We already have so many liabilities, we have to be sure if we take on another, that it can be financially self-sustaining. If it is not able to be financially self-sustaining, we always insist it comes to us with an endowment, which sits in the bank – providing interest payments to cover any annual deficit the property has. The key thing is that if we’re taking on a new property, we find a way to provide its long term financial future. It was with this experience in mind, looking at all the future options for Arundells, that we worked with Sir Edward’s Trustees. If a sustainable solution could have been found for the property, they were really keen to run it themselves, and we would have supported them in that.
Sadly, as you have already heard, we did not manage to find a solution in this instance. The property is very small, the planning restrictions on it are very tight (it has limited permission to open to the public as it is located in a residential area), and very sadly we simply couldn’t find a way to make the figures stack up.
I would think the problems would be similar to Old Thatch, and doubt very much that the NT would be interested in a short-term home of Enid Blyton.
We can share it on social media, maybe some rich person will see it and donate a few million quids. 
