I've seen about 3 of these frames in the past, two on ebay (I wish i'd saved the auctions), and someone asked the same question about a similar frame in the past 12-18 months on the CR list - was it you ?? If not, then I'd suggest you search the archives for information.
To me, the frame can be described as, "A Carlton Giro D'Italia Imitation", made by an independent british frame builder. Everything is there, for a late 60's version of this frame (not the later 70's Carlton models with prugnat lugs, but with slightly different and earlier longpoint lugs.)
I think these were made either by Holdsworth or MKM.
Here are some similar bikes, with identical lugs, but with a different fastback cluster:
http://www.classicrendezvous.com/
I have seen MKMs that were 100% clones of the brampton-victor fastback Carlton Giro D'Italia, as one MKM builder (Dave Marsh) came from Carlton. Why not send an email to Dave Marsh and ask him about your frameset? His email is Carltonflyer@aol.com. Your bike has a fastback cluster with a hole drilled on each side of the "beaver tail" extension of the lug, down the back of the seat tube.
Here is a woodrup with a different fastback seatstay, but lugs more like a carlton flyer :
http://i277.photobucket.com/
http://i277.photobucket.com/
- Don Gillies
San Diego, CA, USA