manc boy,
im going to do the same to mine, i have even got a R19 at the moment but i havnt got round to measuring the back seats yet, i will do it though, i could even try swapping them, the bottoms will be easy i guess, its the backs that might cause more grief,
if the covers and cushions and can swapped onto the clio metals backs and frames they will squeeze in the remainder, and the little bit in the door frames can easily be trimmed in leather,
i will get beack yo you when i know how i get on
by the way the guinee pig R19 is a phase 1 5 door hatch if it makes any differnce, but it did rear hatch and saloon rears are the same