Once quickly looked at one that was presented in poor unloved condition. Very noticable water leaks around main cabin windows ( or long large portholes!) with much staining of interior woodwork. Understand they are a robust blue water boat though.
Looked at one of these - lovely boats as they should be given Rival pedigree! Only comment generally is that it seemed avery long way from the bottom of the companionway to a good handhold in the main cabin. If I went for one I'd want to install something to hang onto when going below in rough weather.
Phenomenal boats - the best of British, along with Rustler. That's my considered opinion based entirely on reputation and hearsay.
Presumably if it's a 42 its's quite recent, as they lengthened the 40 in circa 1998? The 40 had a shoal draft (scheel keel) option, but I don't know if all the 42's were deep keel or not.
They do have a wonderful reputation as a strongly built passage-maker, with proper seaberths etc., and have all the other benefits of a boat designed to be seagoing, rather than as a floating caravan, such as a good wet locker, decent sized chart table etc.
In terms of what to look for - no idea - that's why I get Martin Evans to do a survey.
If it has a teak deck, the Sikaflex may have shrunk back (not just a Bowman 40, ANY teak deck). The internal joinery on the B42 was not exceptional, and a surveyor would only be interested in whether sound, not whether pretty or ugly. From a surveying point of view, as well as all the things a surveyor should look at, there is also the chainplates to be looked at for water ingress and past damage. Other than that, such a sound solid boat which would take a 'dozer to do much damage to.