That & the number of people out & about are reduced. Mind you, at this time of year you never know what you may see.
Ancient woodland is particularly nice in winter. A small forest in Cwm Bychan near to the Dyffryn Burial Chambers is lovely. There is a group of round huts near there, according to the locals, but doesn't appear on maps or anything.
Will dig out what I know about Ashridge. The estate is quite big, even covers Ivinghoe Beacon and the rest of the ridge too. Now that in a winter sunrise is something else.
B