Happened to be standing next to Steve Smith when he got a call from Peter Williams to say there was a Snow Bunt in a field on the Worth Matravers road.
The bird was extremely confiding allowing close approach. However if one got too close, for some reason it would turn back on and kind of look over its shoulder, frustrating a few attempts to get some nice pics. This went on for some time so eventually I got Claire to approach from the other side which really confused it. (see bottom photo)
Aging and sexing wise, greater coverts and primary coverts should give the clues you need. Looking at the greater coverts on this bird the extent of white certainly seems too much for a female but seemingly not quite as extensive as an adult male so perhaps it is a 1st winter male.
The primary coverts would also give a big clue as they are always black in females but will have at least some white in the male but on these photos they look to be covered by the greater coverts.
According to BWP the black centres of the scapulars are rounded in males and pointed in females. Although the rain my have affected the feathers they do appear to be pointed so perhaps it is a female.
Regarding the race, it certainly looks a pale individual with a pale rump which would point to the nominate nivalis
This photo makes me feel quite ill