Thanks for the kind comments everyone. This was the best shot of my afternoon's snapping, taken when I thought I'd "finished", and I'd parked the car to review what I'd got. The opportunity just presented itself through the windscreen - though I got out to shoot! I got down low so the buildings beyond didn't show.
I generally find, Awe, that if I'm shooting an image with a lot of sky I need to underexpose the shot to prevent the highlights in the clouds "blowing" i.e. becoming 255 white. I usually do this with the EV control that, on my camera, allows me to go to -5.0. The ground on this shot, out of the camera, was too dark, so I used the Shadows/Highlight command in post processing to lighten it without affecting the sky too much, then did a touch of masking to bring out the grass detail.
Regards, Tony