They're the last gasp of the Cub (if of course it's original) which as you may guess used the Bantam frame which is quite different from the original Triumph model. They're not nearly as nice looking - Edward Turner, for all his faults, did turn out some beautiful looking bikes - but the Bantam frame is quite serviceable.
ISTR that it used something like C15 forks as earlier Bantam items were rather marginal.
I don't think they're hugely valuable but in decent nick somewhere between £1,000 and £2,000 would be my guess.