The site is protected by Grade I listed building and Scheduled Ancient Monument status.

Thirl [as verb] means "perforated-" or [as noun] "bored-wall",[3] from the Old English þyrel, þyrl, "a hole made through anything, an aperture, orifice" and weall, "wall".

[4] As used and described in an Atlantic Monthly article, it is referenced as "a small passage built into a wall to allow sheep but not cattle to pass through ... a thirl, or a thawl".

[5] In Greek, the word Thura "θύρα thýra, [pronounced] thoo'-rah; apparently a primary word (compare "door"); a portal or entrance (the opening or the closure, literally or figuratively): "door, gate".

[6] The middle English noun thirl likewise references a portal; a through passage, gate or door [thura] through which lambs enter in.