Plug lead and plug on the rocker cover works. Sounds like it could do with a service, if you're not sure on the condition of the basic electrical stuff.
Have you swapped the coil at all? There are 2 different coil types for the TCI electronic ignition systems with different primary and secondary resistances. It could be you have the wrong type fitted if you swapped one off your polo and this may be causing the poor spark. Other than that just make sure all earths and ignition components inc cap and rotor arm are good.
When I changed the coil the part numbers were identical. I have been unable to check the condition of spark as I've had nobody around to turn the engine over for me. I've just changed the rotor arm, cap, HT leads and king leads for an old set which I've had kicking around for a ages - low and behold it started. I'm guessing it was the king lead as the rotor arm and cap look in good nick to me. Thanks for all your help everyone. I'm off to buy a Porsche...
