My agent called me yesterday to say that the Agency has changed their mind.
Instead of waiting to see how I got on with the suggestions for rewrites, and then, if all has gone well, to sign me up, they have decided to take me on anyway, right now. The letter is in the post.
Originally the plan was for me not to send anything in before the middle of March, because my agent would be far too busy dealing with the London Book Fair. The new plan is, if I can manage it, for me to send at least the first couple of chapters by mid-February, ahead of the London Book Fair, so that my agent can tout Lord Alexander's Cipher; or, the Bridekirk Behemoth around editors at the ExCel Centre in London's happening Docklands.
I don't know what has triggered this latest development, but I am very happy about it.