Okay, this last test (it plays the adverts fine) got me thinking - Why would it do this - and ofc, the adverts have checks that prevent a user from wizzing through them.
So, what if the sky go app was receivinga fast forward signal from somewhere my end - so I started the Sky Go app after turning my keyboard off - and it fixed it.
And even better - it remains fixed after I turn the keyboard back on.
My Keyboard (Logitech K360) has media keys, though I have redirected the fast forward and back keys to iTunes rather than windows default - so I am guessing something is wrong there and there is a small bug in the sky go app. Or possibly windows. Or most likely both. Mind you Logitech could be at fault too.
But frankly - I dont care now - It's fixed :-)