Recently bought this frame. Would like to know some more about it as it's quite special.
Some measurements and info:
27.2mm seattube
1" headtube
Ritchey pads
Serial number: S96018449
And try Sunn too, been a few on the forum.
I think they are a generic frame that shops could specify with branding.
A search should find some info guessing too.
Rifle cut tube....merlin uk (not that titanium usa merlin!) As @fettler said.
I recall they were basically a tange tube, made from standard cr-mo, but this was an idea to increase the butting and strength. Tange also tried ditching tubes too for a while....92 team marin etc.
Yours new for about £140 bitd. They also made a prestige version of the frame and a standard tange db without the rifling ......£199 and £120 roughly respectively. Prices from memory.....so.....