Crows v Kestrel

We had an interesting sighting on a local reserve yesterday, it was very quiet birdwise so we were looking at Butterflies and Dragonflies  most of the time when I spotted a young Kestrel making a pretty poor job of hovering over the grassy area. I was then pounced on by four Crows who dogged it for a 100 yards or so and forced it to the ground. The Crows then sat on the fence while the young Falcon crept into the long grass. At intervals one of the Crows dropped into the grass to prod and poke at the young Kestrel before getting back on the fence. This went on for about 10 minutes before the Crows flew off leaving a very frightened looking youngster to flutter into a bush and hide. The Kestrel was still tucked away in the bush when we walked back 30 mins later so it seemed to have survived its ordel,the Crows were long gone. I'm not sure what it was all about, the Kestrel was a bird bred on the reserve as far as we could tell so was on home territory, any ideas ?