I would like to try machine polishing again but it does take minimum of two days with good weather. I'm going to have to wait until the summer to try again as it's constantly raining and gf keeps moaning to stop spending time on my car, hee hee.
I recommend you try one of two "LSP"s (Last Stage Protection)- Either HD wax, as per shoshinsha's suggestion above, or FinishKare 1000P Hi-Temp Sealant. The FK sealant gives a completely different finish to the wax. The wax gives a nice deep dark reflection (where the paint seems to go on and on), whereas the FK sealant gives a glassy effect, as per my pics above. I used to like the deep colour effect that HD wax gives but now I prefer the glassy reflective effect of FK. Both provide amazing weatherproofing and are quite durable.
Let me know if you go for the FK as there's a special technique needed to apply and buff off.