I love Hutton's work. You would probably enjoy his Triumph of the Moon, which is a detailed account of modern Wicca and its various originary myths, and continues the project of subjecting such myths to sceptical historical evaluation, without I think ever being sneeringly iconoclastic.

Interesting thought about Tolkien. Hutton's also written on JRRT, in Witches, Druids and King Arthur.

This rambles, but bear with me.

Hutton has a long history of doing this, and to do so he has to set up a straw man, and pretend that people think the winter solstice was a "Celtic" thing. One problem for his hypothesis is that there really is very little[*] evidence for solstice celebrations among Celtic-speaking people in the British Isles, and absolutely none for the equinoxes.

Such celebrations clearly existed in the Neolithic and Bronze Age, but had died out by the Iron Age. Or at least there's no archaeological evidence of it, and obviously no written records because well, what does the word "prehistory" mean again? And at the very end of that, the Romans had surprisingly little to say about the British Isles, apart from "Aaaaaaaaagh! Picts! Scary!" Hutton has to use the very folklorists he despises when they claim something with which he disagrees.

The winter solstice was a Germanic and Nordic thing, brought by the English and the Vikings, both technically post-Christian in the British Isles, even though neither were when they arrived. Then there's the addition of a fictional Middle Eastern mythology that seems to fit some people's needs, which for some reason decided to celebrate their god's birth on a date that cannot possibly have been the case. But that mythology has so many strange coincidences with well-documented Roman and Egyptian mythologies that it's uncanny. You'd almost think it had a history of syncretism.

But anyway, the winter solstice didn't have to survive that long, as it was re-introduced by non-Christian invaders who turned up after Christianity had been brought to the British Isles. But you can use this to lie convincingly about it not being pre-Christian because, technically, as far as the British Isles are concerned, it isn't.

The contemporary Summer Solstice, on the other hand, is a wholly modern invention, that is fulfilling in a way that organised religion cannot be.

His Hallowe'en hypothesis mostly requires ignoring Scotland and Ireland as hard as he possibly can. Of course there's not much history of it in England - it's not a Germanic or Nordic festival.

One of the great problems of trying to study this sort of thing is that the non-Christian Celtic-speaking people, Anglo-Saxons and Vikings were proto-historic or barely historic. We have bugger all of their own writings for the period concerned, just what other (unfriendly) people wrote about them. The English- and Nordic- speaking people of England become proto-historic again for the period from 1066 till the 14th century, as nothing was written in the vernacular at all, to the degree that it is responsible for one of the Big Questions in linguistics.

But all of that only concerns the nobs. The majority of ordinary people were not literate until the late 19th century, and aren't fully so today. We only have what other people wrote about them, and it was mostly snobby upper-class clergy doing the writing to condemn whatever it was the ordinary folk were up to. The only neutral sources are archaeological, and at best that can tell us that there were festivals at certain times of year (because the shit pits are richer in the same layers as certain seasonal plant matter is found), that certain places were associated with use at certain times of year (again, seasonal plant matter in deposits) and such things. We can only guess as to what it all meant to the people doing the depositing.

But, if Hutton is right, and nothing is pre-Christian, then as a Christian you ought to be thoroughly ashamed of the cultural genocide committed in the name of that religion. Fortunately, I think the celebration at the darkest, most miserable time of year is a natural (non-tropical) human thing that transcends the Approved Superstition du Jour. It exists because we need it, and the power structures accommodate it.

[* None that I can think of, but let's pretend something has come up that I've not noticed]

I think you are being a little unfair on Hutton there - there certainly are people who think that solstices and equinoxes were part of Celtic culture, and not just on the fringes of neo-paganism, so to suggest that it doesn't need debunking because nobody important believes it is to miss the point of what Hutton is doing, I think. One of the things I like about his books is that he gives consideration to even the most far-fetched claims and tries to put them in a real historical context.