That was my theory, Geoff. On balance of evidence it seems more likely that the name was incorrect for whatever reason than that it was correct and everything else is missing. It's not impossible of course, something else complicated could have happened such as being registered illegitimate under mother's name and coming up with Henry later, but everything else seems to match pretty well. I did briefly look sideways, such as wondering if a witness might have been one of her family members, but didn't get far with it. The only real evidence I could think of might be a will for Andrew, or a witness to a sibling's marriage or informant on a death cert (such as Andrew or Margaret's) naming Esther SHORTRIDGE or Robert SHORTRIDGE. Unfortunately independently one would have to spend money to find out, but I did advise checking out any trees that belonged to descendants of Andrew and Margaret to see if any of them have marriage/death certs/more info.
Trish- that's the only one I could find too. The marriage of Andrew BELL to Margaret CARTY was 25 Oct 1830, Torpenhow (where the first two census children of the family were born).