If you look at the greater map of England in the previous post, you can see that Herefordshire was by the middle ages a border region. It was not a center like London, York or Paris. Although fully populated it did not have the same crush of people that London did. For the sake of this treatment I am going to assume it is equivalent to a role playing average or smallish holding (King,Knight,???). Depending on the world and the game needs I'm sure the leader could have any title. I'm using it to create a middle of the road rule of thumb.
First, the over all size.
At its longest its about 44 miles. It is roughly 40 miles in diameter. Looking at the list of possible towns I count 24 identified sites. I'm not too hung up on details (This is a game after all) so I'm going to take this as a maximum of concurrent towns in a region.
There were only 8 Medieval towns present after 1500 in the region. Of the 24 possible I'm going to reserve 8 as dominant and either town sized or better.
(see first pic - this post)
There are a known collection of 13 failed towns. I'm going to reserve that many struggling or really tiny towns. This will include little Abbeys or wierd game elements that aren't supported by trade and commerce.
(See Second pic - this post)
Now looking at the surviving towns in 1500 they have a noticable space between them, whereas the failed towns are sort of clusterred. This might be for all sorts of reasons but I'm going to interpret that as a radius necessary for a successful town.
This really is very arbitrary. Population pressure can make bigger cities out of close small towns - as happened in London. The failed towns could have been grouped around resources or leaders that were unsuccessful etc... Stil this will be my rule of thumb.