Finally, there was the "hard thinking" which I did during the journey, inspired by a rather important letter regarding my mortgage in Newcastle that arrived in the morning.
As a result, I arrived in Manchester, a little later than comfortable, and not in the right mood or energy level to be funny. The excuses have now been made official.
As I wasn't feeling it, so neither did the audience. It was somewhat disheartening, and I got out of the place rather promptly. Luckily, the CDs I'd bought at lunchtime in Tesco were enough music-therapy to get me home in a cheerful frame of mind. You win some you lose some.