This is the only blurb I've ever been able to find about frame 2.
They're as rare as hens teeth.
From what I can gather. The remainder of the UK frames were bought by a Dutch distributor and marketed under another brand name. Common practice at the time.
The bike in the photo is a Merlin, for a long time, Merlin Cycles used to offer a steel frame that they called a TDB (for Tange Doubled-butted) and their blurb said it was made with 'the latest Tange Spiral-butted tubeset', so although I've never seen another one, I presume the bike in the photo is one of those TDBs. It has a spiral-butted seat tube as well. It looks as though the spiral is an externally-applied butting, which must strengthen the tube, perhaps sufficiently to enable a thinner-gauge tube to be used.
The TDB used to sell for £135, whereas the Merlin WCS, which was made out of the highest grade of Tange/Ritchey tubing, was £199. As ever, these were very good value frames, always highly-praised. I imagine that the TDB wasn't heat-treated, but would have been at a level just below Prestige. i.e., at or slightly above the quality level of a generic 4130 db frame.
I don't know of any other manufacturers that used the spiral-butted tubeset, but Tange dominated the market in those days, so if they were making it it must have been fairly widely used.
All in all, it's a very good frame and a notch above the usual chromo 4130 of that period.
Don't see how you can go wrong at this money.
The tubing feels like a 20 pence piece.
Hope this helps.