The short answer to that is I don't know, but given that access is provided under sufferance in much of Shropshire, as the guidelines of the landowners national body suggests, I expect that a minimal level is overlooked and the usual disclaimers have appeared in that area and stay for the life time of an A4 pocket.
At the risk of highjacking the OP's topic I will say no more.
This is a beautiful area of the county, well worth the visit from Birmingham. One of my abiding memories of the pathways from Aston to Sibden was the proliferation of Dog and Apple Rose, but perhaps this year it may be a tad early for the full impact of this beauty.
If one of their walks reaches Hopton Castle, there is an interesting bit of Civil War history explained on the visitor information boards.
Why is it good walking country? I think much of south Shropshire together with mid Wales is deceptive. It provides much rolling countryside, with ever revealing views without the long hard climbs of steep hills. Choice of route can exploit this property of the terrain. A work colleague of Mrs BWW's, claimed to have a limit of 3miles walking, was sitting with us on the ramparts of the Burrow, drinking coffee, when I explained we had just walked 5 and a half miles, through a haze of atomised coffee, I was told that she could only walk three miles.
Later in the Kangaroo, I bit on my tongue, when I nearly told the full distance we had walked for fear of a more solid expression.