I went to schoool with all four of the Thyrds - we're taking about 50 odd years ago but as I recall they were: Paul Ellis - Vocalist & Lead Guitar (also composer), Mike Hughes - rhythm guitar, Johnny Malcolb - bass guitar and Mick Teasdale the drummer.
Mick Teasdale was a class-mate and a friend (until he nicked my girlfiend) - he lived in Pimlico and I think Paul Ellis lived nearby, but as the school was in Clapham Junction and many of the pupils came by train, Kent is a possibility. I have a picture of the four of them if you're interested.