I thought I would resurrect this thread with some recent findings in case it is of any use to anyone considering burying a head. I have now tried three methods: boiling, cold water maceration and burying, and have put down some of my thoughts below. I am no expert and am sure there are others who could offer sound advice on how to perform these methods more effectively than I did.
Cold Water Maceration
I tried the cold water maceration method first, skinning the head, submerging it in water up to the coronets and adding biological washing detergent to the water, then regularly changing it. It took an age and of course came with the inconvenience and smell of a decaying head in a bucket in my garden. The head came out fairly clean but the bone still had residual fat in/on it and I couldn't get rid of this completely. I bleached it and it came out okay but areas of the skull were brittle and loose by the time it finally emerged 'clean'.
Burying
I buried the head of a decent fallow buck taken back in March and have just dug it up. First impressions were pleasing: the skull was virtually clean of all tissue bar a few bits of skin and hair which were dry and just peeled off. There was some fatty residue remaining inside the eye sockets but this was also dry and came out with little persuasion. What was immediately noticeable however was the discolouration of the skull, even after considerable hosing and cleaning with a toothbrush to remove all remaining soil. It had a deep yellowy-brown hue to it and the bone was also noticeably more brittle. I then ended up boiling it in a bid to remove the fat/grease from the bone and then bleached it as usual, but the colour has not come up anywhere near as white as the other heads I boiled. It still has that yellowy brown hue.
In short, if it's a head you care about or want to display, my advice is to puyt in the extra work and boil it; the results really are worth it.