This is a question for the woodland stalkers rather than those on the hill.
My understanding is that it is not illegal to leave the gralloch/pluck/legs/head at the shot site as wild deer are exempt from disposal regulations at the shot site. If you take them back to the larder to remove pluck/legs/head then you do come under the legislation and are required to dispose of the parts properly. I do know you are not meant to dispose of anything within 50 meters of a water course.
The public do tend to get a little disturbed when fido comes back with a Roe head in his mouth after ferreting around in the bushes, and some land owners get a little revved up when they stumble upon our leftovers.
Some stalkers I know always bag up the parts and dump them in a corner of the estate on the grounds that if you leave parts lying about it puts other deer off. Others bury the parts but I'm sure they are dug up my Charlie soon afterwards.
So what do you do?