I decided that the core of the Elder Wand is the tail hair of a Thestral; a powerful and tricky substance that can be mastered only by a witch or wizard capable of facing death.

Having taken Harry’s blood into himself, Voldemort is keeping alive Lily’s protective power over Harry. So Voldemort himself acts almost like a Horcrux for Harry – except that the power of Lily’s sacrifice is a positive force that not only continues to tether Harry to life, but gives Voldemort himself one last chance (Dumbledore refers to this last hope in chapter 35). Voldemort has unwittingly put a few drops of goodness back inside himself; if he had repented, he could have been healed more deeply than anyone would have supposed. But, of course, he refused to feel remorse.

Voldemort is also using the Elder Wand - the wand that is really Harry’s. It does not work properly against its true owner; no curse Voldemort casts on Harry functions properly; neither the Cruciatus curse nor the Killing Curse. The Avada Kedavra curse, however, is so powerful that it does hurt Harry, and also succeeds in killing the part of him that is not truly him, in other words, the fragment of Voldemort’s own soul still clinging to his. The curse also disables Harry severely enough that he could have succumbed to death if he had chosen that path (again, Dumbledore says he has a choice whether or not to wake up). But Harry does decide to struggle back to consciousness, capitalises on Lily’s ‘escape route’, and pulls himself back to the realm of the living.

It is the last piece of soul Voldemort possesses. When Voldemort attacks Harry, they both fall temporarily unconscious, and both their souls - Harry's undamaged and healthy, Voldemort’s stunted and maimed - appear in the limbo where Harry meets Dumbledore.

I know that after Dudley’s brave attempt at reconciliation at the start of Deathly Hallows, the two cousins would have remained on ‘Christmas Card’ terms for the rest of their lives, and that Harry would have taken his family to visit Dudley’s when they were in the neighbourhood (occasions dreaded by James, Albus and Lily).

Where did the last four months go? It feels as though Hallows was published, and then I slipped through some strange time portal in which everything went at double-quick time, only to be spat out in early December.

People keep saying to me, ‘I expect things have calmed down now you’ve finished?’ to which my answer some days is a fairly humourless laugh. I have been exceptionally busy since July, what with the US/Canadian tour, Beedle the Bard, assorted charitable commitments, a massive post-publication mountain of correspondence, plus those three children I insisted on bringing into the world. Consequence: neglect of website!

As for mourning Harry – and I doubt I will be believed when I say this – nobody can have felt the end as deeply as I did. The writing of Harry Potter has been inextricably linked with my life for seventeen years, and saying goodbye has been just as tough as I always knew it would be. So I want to say a huge thank you to everyone who has written to me since publication, saying such wonderful things about what the books meant to them, because your words meant the world to me at this very bittersweet time.