Being a lay man i was never quite sure what you meant by a horizontal be-heading. This is because i had always presumed that the victim would bow their head. I take it that you mean by this, that the victim was standing with the neck vertically when the sentence was carried out ? I had to think about what was meant by a "horizontal be-heading" for quite a while. In the TV series "Henry the VIII" I thought that Anne Bolien had her head down when it was time.
Can't believe you experts got me thinking for so long about what a horizontal executioners stroke was !
p.s.
i've never worked out if there is a spell checker on this forum. Does it exist ?