Can anyone tell me how to obtain a green lawn and keeping it green, I find in different weathers the grass changes, one minute it will be lovely and green,next all brown and horrible, I'd love to get it to a nice green colour and keep it that way, all tips appreciated.

I would suggest watering (assuming there is no waterban in your area) and using a good fertilizer to keep the grass green

I typically do one application of iron per year. This keeps my grass nice and green without the rapid growth (less mowing).