Bumper Undercoat and compatible top coat
 

I find I have two unopened spray cans ( plus lacquer) of White Gold that are ‘genuine MG Rover’ – pretty sure purchased from Rimmers . These are no longer available. I aim to use these where some kind drivers rubbed the rear bumper of my car but I have a problem concerning an undercoat :-

1. These bumpers are plastic and I read that a special type of undercoat is required for them ?
2. I am aware that paint manufacturers have changed paints to be ‘water based’ these days but I assume the original MG Rover ones ( and my Rimmer ones) are NOT of this nature – so where can I get an undercoat spray can that I can use ?
3. May be better to buy some newer White Gold spray cans / undercoat – but , again , is a special undercoat needed for plastic bumper ?

Of coarse I could always ship my bumper to the local body shop but it’s likely to cost over £300 and I don’t have money to burn. Besides , reckon that , with advice , I can get satisfaction from doing it myself.

Any observations on the points above and how to proceed most welcome.

When I changed the rear bumper on the other half's Rover 25, I went to a local paint supplier to get an aerosol matched. I also asked them about a primer suitable for plastic bumpers and they just told me to use a standard etch primer, which I did and it worked fine.

Good advice
 

Following the last post I am going to try Halfords Etch Primer since I note they say it has bonding for plastic and also works on old type paints.
I will also be trying out some chrome paint across the whole of the lower grille area ie where fog lights etc go. I saw an early MR Rover setup with this arrangement and it looks quite nice - worth a try anyway.