KaTe Bush was David Gilmour's guest during a performance of Pink Floyd's "Comfortably Numb" at his Royal Festival Hall show on January 18, 2002. KaTe sang the part of the Evil Doctor. Below are two different audience recordings of the performance.
The recordings were provided to me on an audio CD by George the Wipe. The audio was extracted with Exact Audio Copy and encoded to 128kbps mp3 files with LAME 3.89 MMX (with the -h switch set).