Meguires polish

I presume you are referring to ABS plastic. My old caravan was a bit dull and, despite copious amounts of Mer and elbow grease, the mirror shine never returned although it looked passably shiny.

Hi I believe the front is made of GRP

From my yachting experience, oxidation of the gel coat of GRP is a common problem.  A fine rubbing compound should do the trick, before applying a good quality wax polish.  Polish alone, won't do it.  I would be very careful, however,  to use a very fine compound because I doubt that the gel coat on caravans will be as thick as on boats. I think you might find that T-Cut is a bit too aggressive, but a visit to any yacht chandlers will provide you with an array of finer alternatives.

Another tip is to avoid using common detergents when washing the van - nearly all contain salt which will very quickly remove the polish you have spent ages applying.  I only ever use good, old fashioned, Stardrops - because that doesn't contain any salt.

Hi thanks very much for that advice

I know this isn't a polish but I have been using this for a while I have never used a polish just give the van a good cleaning with this and the sparkle is there.

http://www.cloverchem.co.uk/2013/uk/product_detail.asp?prod_code='403'&range_sub='31'http://www.cloverchem.co.uk/2013/uk/product_detail.asp?prod_code='403'&range_sub='31'

If you look at the data sheet, this also contains salt.