Friend of mine had a Merlin Cycles own brand frame back in the 90's, that's exactly what came to mind when I saw the first pic... the second one showing the twist pattern confirmed it for me, but I'm probably wrong!
originaly the previous owner did try to pass it off as a kona ti but wasn't quite convincing enough anyway heres a few pics of how the bike looked before it landed with smiffy16v it may give you a better idea,
Good shout from P20 on the Merlin - the finish reminds me a lot of this Tange steel frame I bought from them around '04 (though it was NOS at the time). All other dimensions/fittings look the same too at first glance (including the position of the Tange sticker). Mine was stolen within a week of building up as a cheap commuter, but not before I took a photo or two...