Im a firm favorite of the Blue bottled Mer polish,doesn't leave any white powder marks, as for Mr Wogan I think he uses bullshit and his right hand for polishing. 4D
Try starbright marine polish with teflon,its simply the best and much much better than Autoglym in the shine department,but you'll have to go to a chandlery to buy it.As for your plastic bits try STP son of a gun.