On today's ride, nice and bright day, Peterborough to Stilton, round a few villages, 90% of it through quiet farmland, Red Kite and Buzzard are plenty, you will often see them on the ground and today I saw what appeared to be a buzzard at the verge of a field / ditch...but it had a very distinctive white rump, get my camera out for a photo...and off it went before I had chance to even get a poor shot at distance. So, possibly a hen harrier.
Ironically, less than a mile later, a buzzard in similar circumstances, took off as I approached, as said earlier, a modestly regular thing to see.