This performance, which I only found out about yesterday, was ostensibly about the restless spirits trapped inside books. Momus (attired all in black, including a hood) played the role of a spirit medium specialising in spirit media, as it were, or more precisely in the spirits of dead people trapped in books.
He invited attendees (of whom there were perhaps 10, presumably because those attending only had a day's notice of the event) to choose books at random and read a sentence from them, which he then would spin into a tangent, philosophical reflection or evidence of eldritch and unholy things beyond the veil between worlds. (In the first example, a cheerily banal line in colloquial English turned out to really be in "Ukrainian", and a portent of grim things indeed. Later, a book of knitting patterns revealed the battle between Jesus Christ and the tamagotchi—perhaps an echo of Momus' writings about the dualism between the Judaeochristian sex-death-guilt culture and the Shinto fertility religion, though he didn't labour that point.)
In between the entertainment, he performed a few songs, including Beowulf (which he did from under a blanket) and Robin Hood (with a dig at Thatcher Blair Brown's devil-take-the-hindmost Britain), singing over an iPod playing through PC speakers, and playing the odd stylophone solo.
He also played one of the songs from the new album he's working on with one of the chaps from Gay Against You; it was built up from a Magazine sample (and thus, he said, possessed by Howard Devoto's restless spirit), and sounded quite good, in a glitchy breakcore sort of way; not too unlike Kid606 or Talkshow Boy.
Anyway, Momus' own account of the gig, with more details, is here.
Momus will be back in London in late June, when he will be wandering the south bank of the Thames and telling tourists that they're in Tokyo or something like that. Which should be worth going along to.