[Formendacil]

I believe that the truth of the matter is that Tom Bombadil is a "Merry" fellow. In other words, he is most obviously Merry's alter ego.

After all, it was Merry who led the Hobbits into the Old Forest. Merry had "disappeared" (they say he was in the willow, but we only have Pippin's word for it- the Fool of a Took). Thereafter, in the House of Thomas Meriadoc Brandywine-Bombadil, we are given no scenes of Merry and Tom directly interactly. I would theorise that Merry's accomplice Goldberry (aka Estella Bolger- also known as Fatty*) used some rather potent brews to confuse the Hobbit's minds and make them think that Merry was with them as well as Tom.

Now, it must be obvious therefore that Estella was again playing a covert role when Merry, Pippin, and Sam are captured by the Barrow-Wight, since Merry ole Tom shows up not long after to save the day.

Finally, at the edge of the Old Forest, under the cover of dusk, Merry and Estella again trade places, so that Goldberry/Estella/Fatty remains behind (and gives word to Gandalf) while Merry continues on.

Obviously, this was the whole reason that Merry goes on the quest, so that Tom Bombadil can face and defeat the Witchking. One may ask why he didn't do it at Weathertop, but the answer is that he was still being affected by lingering effects of the Prancing Pony's ale. Besides, he didn't want to blow his cover.

Gandalf obviously knew about this, which is why he was so adamant that the Ring be destroyed and not sent to Tom. After all, Tom was right there with them. Furthermore, at the end of the story, when Gandalf disappears to "visit Tom", the reason we are never shown the scene is that it never happened- Gandalf was actually visiting Estella, who, as Fatty, was actually in the Lockholes at that time. Hence, Gandalf was actually helping to save the Shire, not just buggering off leaving the responsibility to Pippin and Sam.

There you have it. Tom Bombadil is Merry Brandybuck with boots and a beard.

*That Fatty is actually Estella may be easily shown by the fact that Fatty is never referred to by Fredegar. Besides, why do you think that Merry went ahead with "Fatty" instead of hanging out with his closer chums Frodo and Pippin?