Well, they're American rather than British, but the Grateful Dead songwriting team of Hunter/Garcia ~ especially lyricist Robert Hunter ~ are a pretty unique in how they wrote songs drawing upon American folksong traditions. While most of the arrangements and performances were more "rock" than "folk" in terms of overall sound, the melodies and lyrics were in many cases *very* traditional.

Many of Hunter's song titles either duplicated titles of traditional songs or quoted memorable lines of traditional songs, e.g., "Shake Sugaree," "Mississippi Uptown Toodleoo," to name just two off the top of my head.

The above, of course, may be more pertinent to readers of this thread than to MurkeyChris, who is concentrating on British song.

In the Brit universe, I would second the nomination of Ewan MacColl, many of whose most famous songs are *often* mistaken for traditional folksongs. You *can't* leave him out of that dissertation!