OS Boundary-Line MHWS data appears to be wrong for these two - their geometry exactly matches the admin boundaries from Boundary-Line, and the MLWS shape from OpenData StreetView, which implies that they are also MLWS rather than MHWS.

According to OpenData StreetView, there are two tiny bits of skerry that are above MHWS (within ways 30452363 and 30452364 respectively) - I just didn't bother to add these because they're so small.