I presume this is a scheduled monument and therefore enjoys some protection.
However, there seems to be no official public footpath to the site - not shown on the Explorer map, or on the info board next to the wooden stile at the road layby (approx SY601869 - almost opposite Hampton Barn Farm). But there is a clear concrete stile into the bottom of the field where the burial chamber is, and near the hellstone I remember a wooden signpost, about 10 metres from the burial chamber (see moey’s or joolio geordio’s pic).
So what happens if a landowner (in this case, or another case) says that they will ‘protect / look after’ the monument but not let anyone see it??