Hi WP, unfortunately it doesnt get unstuck that's the problem, it just stays on the smaller chainring and the shifter remains ineffective. The brand new cable was as I installed it, i'm pretty sure I did it okay, i'm normally quite adept at these things, i've built bikes from sctratch before so doing one cable was no biggy, although getting the shifter to work seems beyond me. Conversely though I have been known to miss the blindly obvious so it could just be me being a doofus.

Indyguy, thanks for the idea, but I've already tried switching the positions on how the cable attaches to the FD and no joy. Thanks for the idea though.