ROUGH LEGGED BUZZARD?

For the past few days we have had a buzzard flying around our area - we watch it come over the hill and fly down towards our garden being mobbed constantly.   Ordinary Buzzards flying nearby look somewhat smaller and it is almost pure white underneth with a definete black edge all around it - it looks beautiful against the winter back drop and very distinctive.   It appears to have a white rump as it turns but most sightings are of the underside - has anyone seen a rough legged buzzard in Shrewsbury/Shropshire area as I'm sure this is what I am seeing.   The other buzzards come down and sit in our scots pine but this one just circles and keeps quite high and distant from us in comparison.