The sound of people singing desultorily while taking shelter in the Tube floated up to them.

Here the witch said "Yoop" to Harold, and he reared and shot upwards, narrowly missing the statue of One In A Bus-catching Attitude, which marks the middle of the Circus.
As soon as the witch had out-distanced the noise of expectant London, she heard quite distinctly the approach of London's guests.

They came with a chorus of many notes, all deep and dangerous.
There were a few clouds wandering about among the stars, and to one of these the witch and her faithful Harold repaired.

A cloud gives quite reasonable support to magic people, and most witches and wizards have discovered the delight of paddling knee-deep about those quicksilver continents.

They wander along shining and changing valleys under a most ardent sky; they climb the purple thunderclouds, or launch the first snowflake of a blizzard; they spring from pink stepping-stone to pink stepping-stone of clouds each no bigger than a baby's hand, across great sunsets.