Why isn't it already fenced Swb?
Yes it is fenced however the fence does not correspond with the OS maps thats the issue.
Left hand map registered with land registry for the sale of the yellow box from my land its a radio tower. My land is parcel number 5283 & 5783 this is the map registered with the LR in 1980. Non of my land has changed shape ever. Middle map shows the correct lines for parcel 5783 it also shows the correct position for the radio tower map one shows it against the boundary line which it is not. Map three on the right shows the woodland trust land now overlapping and creating a new line touching the radio tower. You can see the correct boundary line is still in place but now absorbed in to the trust land.
The bottom map is one I have had commissioned it shows by current bounders marked in pink the line in black is where my boundary should be in accordance to the OS maps and historic documents.
Frustrating to say the least.

