Thanks all. This may well be fairly common but heres how i got the colours in case anyone is interested......
I use GIMP but i'm sure the same principles apply to PS.
Duplicate the image as a layer
Convert one to mono with OTT (over the top) contrasts, black sky and bright bales etc
Up the saturation of the colour layer significantly so that it is also way OTT
Make both layers visible with the colour version on top
reduce the opacity of the colour version until you get the right balance between depth and vividness
flatten and done
It allows you to get nice depth without oversatuating and seems to work well with landscapes. obviously not everyones cuppa but one to play with.