Absolutely loving the help and support from experts on here, thanks so much guys and gals.
@Splefix - that's an awesome idea, thanks for the suggestion.
@JonB - yep, this is exactly what I ended up doing, Jon. Once I had my head around the logic and syntax, even this old chap managed to code this section in a few mins.
Still a few things to iron out in the code, but all in all, for my first real attempt at a slightly longer Python script than Print("Hello World:), I am pretty pleased with myself.
Connect4 coded in Pythonista and running (albeit with a few glitches) on my iPad. Who'd have thunk it!! haha