So there it is: Peter Jackson's forthcoming brace of Hobbit movies will be individually titled The Unexpected Journey and There and Back Again. Not the most exciting news to emerge from Wellington, where Jackson and his team are hard at work shooting his Lord of the Rings prequels back to back, especially as we had a pretty good idea this was going to be the case when it was reported in March that Wingnut films had registered both titles. The individual monickers do add to the continuing sense, however, that Jackson is working hard to forge a Rings-style high fantasy epic from rather unlikely source material.

I first commented on this phenomenon back in December, when it emerged that Orlando Bloom and Cate Blanchett, aka Legolas and Galadriel, might be appearing in The Hobbit (even though their characters are not present in JRR Tolkien's 1937 children's tale), so it's nothing new. Tracking the little clues that tell us that Jackson wants a radically souped-up Hobbit – and mulling over whether the manifestations of this desire will end up being intelligently crafted or hamfisted on the big screen – has, however, become something of a hobby recently, especially as more and more details begin to emerge.

Along with the titles, whose individual monickering of course mimicks that of the three Lord of the Rings instalments, Jackson this week revealed that we will see the White Council, aka Gandalf, Saruman and Galadriel, attacking the evil Mirkwood fortress of Dol Guldur. In the book, we only hear about the driving out of the Necromancer (revealed in Rings as villain Sauron) in retrospect from the lips of Gandalf.

"I'm not going to say just what and when, but I will confirm that both the White Council and Dol Guldur will feature in the movies," wrote Jackson on his Facebook page. "And not just in one scene either. Just how to visualise it has been a challenge, but fortunately [design chiefs] Alan Lee and John Howe went crazy with ideas, and it should look pretty cool."

It's certainly a tantalising prospect. What shape will Sauron take – Tolkien offers no clues – as he will presumably not yet have assumed the form of a great eye in which he appears in Lord of the Rings? And does this mean that the 89-year-old Christopher Lee has made the trip to New Zealand after all to reprise his role as Saruman? Perhaps his part will be shot against blue screen in the UK – we may have to wait a while to find out.

Structurally, of course, the presence of the scene further Lord of the Ringsises (apologies for the clumsy phrase) The Hobbit. Tolkien's book is a gentle, linear fable which rarely leaves Bilbo Baggins's side (the brief period at the end of the story when the great dragon Smaug leaves his lair to rain down fire and terror on nearby Laketown, and later when the hobbit is asleep during the battle of five armies are the only instances I can recall). Lord of the Rings was a sprawling narrative which split and split again over the course of the book, following different members of the original fellowship of the ring on their separate adventures. Pulling us away from the central story will present The Hobbit through a very different prism to that which was originally intended.

Having said this, Jackson is really only doing what Tolkien himself attempted to do after the publication of Lord of the Rings. The author also revised his earlier tome in an effort to smooth out stylistic differences. Gollum was made more sinister and his dependence on the ring more unnerving in the 1951 edition, but a later more radical revision was abandoned after Tolkien realised he would have to make too many changes.

On the positive side, the presence of Saruman, Galadriel, Ian Holm's elder Bilbo, Legolas and even Elijah Wood's Frodo (goodness only knows how they are going to shoehorn him in) ought to make The Hobbit movies feel like a genuine prequel project. Part of me says more power to Jackson, who has already shown he has the chops to prep difficult material from the same author for the big screen. The other part bristles at all this tinkering with Tolkien. I can already see myself being jolted out of my reverie in the cinema in six months' time when Bloom pops up out of nowhere, his shiny elf hair flailing out behind him in the wind, to take out some poor Orc who's been threatening mischief. "That's not in the book!" will be the thought going through every Tolkien reader's mind, but maybe ... just maybe .... we might be better saving our outrage for more important battles.