Revolution 9 (13)
I've gathered together source information on some events that took place in London in late 1966, 1967 and early 1968. The summary below includes other dates of interest.
1966 September AMM Concert AMM Paul
October IT Launch AMM, Pink Floyd, Yoko Ono, etc Paul
November Unfinished Objects Yoko Ono, (AMM) John
1967 January Carnival Of Light (Beatles tape) ??? Paul?
April Technicolor Dream AMM, Pink Floyd, Yoko Ono, etc John
1968 April 2001 Strauss, Ligeti, etc John
The International Times was an underground paper that was launched in London in 1966. McCartney helped out with the venture. There is a picture of Lennon from late 1967 at home reading the IT (with Beefheart Safe As Milk posters on the fridge).
A Carnival of Light is probably what we now call a light show.
AMM Concert (September 1966)
McCartney was one of a dozen in the audience at an AMM concert in London. The Harrison's had left for India the day before. Lennon was just about to leave for filming How I Won The War.
AMM performed at some of the other events. They had included live Radio feeds in their recordings in 1966.
International Times Launch (October 1966)
The launch of the underground newspaper took place at the Roundhouse, with Pink Floyd in attendance. McCartney attended as well. Strangely, Miles has missed this date in his diary. Incidentally, this event shows conclusively that McCartney had returned to London after meeting with Lennon and Epstein in Paris on September 19.
On 15 October  the new underground newspaper the International Times or simply 'It', as it came to be known, was launched on a cold night with a huge event at the Roundhouse in Chalk Farm, London. Miles: 'We did fliers for the IT launch to publicise it, printed on letterpress, with the actual IT girl on it, Clara Bow. We printed thousands and gave them away or mailed them to people.' Using Hoppy's address book, Miles and Hoppy sent out invitations that circulated among the hip coteries of the emerging underground.
Peter Jenner said 'Paul McCartney was, dressed as an arab in a hood. It was very dark. The total power supply in the Roundhouse at that time was about as much as there was in the average kitchen, probably much less. So the Floyd frequently put all the lights out; we frequently blew the power. If you saw the place in daylight you would have been horrified. It was dank, really cold and wet and filthy and horrible but the excitement at that gig was enormous. It was like 'Wow! This is our place.' There was this great feeling; it was a classic gig, a terrific gig, and there was the Floyd and there was the Soft Machine.'
The Soft Machine played their first gig as a quartet, going on at 9 PM. They had borrowed a motorcycle, parked it onstage and fitted it with contact mikes on the cylinder head, and its short bursts of noises as it was revved echoes throughout the Roundhouse at intervals through their performance of their psychedelic-laced jazz improvisations. Halfway through their set, all the lights were shut off, and in the darkness came the amplified voice of a Japanese woman. It was Yoko Ono, staging a Fluxus-style Happening.
"Touch the person next to you....." she said, and the startled audience responded, reaching in the dark for the person next to them. A flurry of embarrassed giggles and then the lights came back on and the Soft Machine continued their set. Ono, who had been active the German/American experimental arts movement Fluxus in the early 1960's, was a familiar figure in the nascent Underground.
On November 9th, just a few weeks away, she would meet John Lennon at Miles and John Dunbar's Indica Art Gallery. Lennon had come down to see her Unfinished Objects and Paintings show.
"Yoko One came around to Cromwell Road," says painter Duggie Fields, "she wanted me be in her Bottoms movie which I found uninteresting. Now I wish I'd gone and talked to Yoko when she came to Cromwell, even had my bottom filmed, because she was a very interesting woman."
Keith Rowe of AMM says, "We had a very good relationship with Yoko. She used to stay at Cornelius Cardew's flat, and the AMM played at the opening of her exhibition. We knew her quite well." http://www.furious.com/perfect/sydbarrett.html
Unfinished Objects, Yoko Ono (November 1966)
The infamous Unfinished Objects and Paintings show at John Dunbar's Indica Gallery where Lennon first met Yoko Ono. AMM provided music for the opening. However, Lennon would not have heard this at his preview the night before the show opened.
Carnival Of Light Rave (January 1967)
In December 1966 McCartney was persuaded to provide music for a Carnival Of Light Rave while working on Penny Lane.
Paul wrote Penny Lane in the music room at Cavendish Avenue, on the piano which had recently been painted with its psychedelic rainbow by David Vaughan. In December 1966, about the same time as he delivered the piano, Vaughan asked Paul if he would contribute some music for a couple of Carnival of Light Raves that Binder, Edwards and Vaughan were promoting at the Roundhouse as part of their idea of bringing art to the community, in this case in the form of light shows, experimental music and films. David: 'I asked Paul to do it and I thought he would make more of it than he did, I thought this was a vehicle for him, if anything was. Miles, Many Years From Now
On January 4, 1967, the Beatles recorded the infamous unreleased track:
After completing dubs for Penny Lane, McCartney led the Beatles through the taping of an untitled piece for the Carnival Of Light Rave planned for later in the month. Each track seems to have been filled separately, mostly with distorted rock instruments. Sound effects and screamed vocals were also used. The track was mixed for stereo and taken away by McCartney.
Amazingly, perhaps, Paul agreed to make a contribution, despite being in the middle of the recording sessions for Sgt. Pepper. So it was that on 5 January, after overdubbing a vocal on Penny Lane, the Beatles under Paul's direction freaked out at Abbey Road, producing an experimental tape just under fourteen minutes long. The tape has no rhythm, though a beat is sometimes established for a few bars by the percussion or a rhythmic pounding on the piano. There is no melody, though snatches of a tune sometimes threaten to break through. The Beatles make literally random sounds, although they sometimes respond to each other; for instance, a burst of organ notes answered by a rattle of percussion.
The basic track was recorded slow so that some of the drums and organ were very deep and sonorous, like the bass notes of a cathedral organ. Much of it is echoed and it is often hard to tell if you are listening to a slowed-down cymbal or a tubular bell. John and Paul yell with massive amounts of reverb on their voices, there are Indian war cries, whistling, close-miked gasping, genuine coughing and fragments of studio conversation, ending with Paul asking, with echo, 'Can we hear it back now?'
The tape was obviously overdubbed and has bursts of feedback guitar, schmaltzy cinema organ, snatches of jangling pub piano, some unpleasant electronic feedback and John yelling, 'Electricity.' There is a great deal of percussion throughout, again much of it overdubbed. The tape was made with full stereo separation, and is essentially an exercise in musical layers and textures.
It most resembles The Return of the Son of Monster Magnet, the twelve minute final track on Frank Zappa's Freak Out! album, except there is no rhythm and the music here is more fragmented, abstract and serious. The deep organ notes at the beginning of the piece set the tone as slow and contemplative. Miles, Many Years From Now
Lewisohn describes the track as follows:
...it was a combination of a basic track and numerous overdubs.
Track one... was full of hypnotic drum and organ sounds;
Track two had a disorted lead guitar;
Track three had the sound of a church organ, various effects (the
gargling of water was one) and voices
Track four featured various indescribable sound effects with heaps
of tape echo and manic tambourine.
But of all the frightening sounds it was the voices on track three which really set the scene, John and Paul screaming dementedly and bawling aloud random phrases like "Are you alright" and "Barcelona" Paul terminated the proceedings after almost 14 minutes with one final shout up to the control room: "Can we hear that back now?"
They did just that, a rough mono mix was made and Paul took that away to hand over to the Carnival Of Light organisers... Geoff Emerick recalls this most unusual session. "When they had finished George Martin said to me, "This is ridiculous, we've got to get our teeth into something a little more constructive."
Twenty years on, George had obviously driven the session from his mind, for when reminded of the sounds on the tape and asked if he could recall it, he replied, "No, and it sounds like I don't want to either." Lewisohn CBRS92
On January 28, 1967 and February 4, 1967 The Carnival Of Light Rave was held at the Round House in London. The Beatles did not record on either of these Saturdays, so they would have been free to attend. Miles' Diary reports McCartney and Harrison as attending the Four Tops concert at the Royal Albert Hall in a concert arranged by Brian Epstein.
I haven't found any information regarding performers or attendees. The show may have had the same structure as the October 1966 IT launch.
Technicolor Dream (April 1967)
April 28-30, 1967 14-Hour Technicolor Dream
Over fourty artists, including Pink Floyd, Yoko Ono and AMM, performed. The Beatles did not record on any of these dates. Lennon was tripping with John Dunbar at home on the 29th when he decided to go to the show after seeing a television report (Miles' Diary).
The event which did most to spread the word about British psychedelia and the underground was the 14-Hour Technicolour Dream at London's Alexandra Palace between 28 - 30 April 1967 at which Pink Floyd, The Crazy World Of Arthur Brown, The Social Deviants, Tomorrow, The Pretty Things, The Purple Gang and The Syn (who wrote a song about the event) were among 41 bands who played on two stages amid a carnival of light shows, posters, theatre groups and a fairground helter skelter while the audience included John Lennon.
The show was a benefit for the underground newspaper, International Times, which had been busted by the Vice Squad and the establishment continued their harassing of the scene, busting several bands including The Rolling Stones and shutting down the pirate radio stations Radio London featuring John Peel's legendary Perfumed Garden show, Radio Scotland and Radio 390 and 270 which had sprung up, broadcasting from boats out at sea, outside the British
territorial waters. Still, Radio Caroline managed to defy the ban by moving its offices to Amsterdam and Paris. In response, the BBC set up Radio One but it was many years before UK radio enjoyed the range of music that has been part of the American way of life http://www.delerium.co.uk/archive/uk6070s/introduc.html
2001: A Space Odyssey (April 1968)
One the major events of 1968 was the release of Stanley Kubrick's monumental film. It opened in London on April 11 at the Casino theater. In Manhattan the film had a run of over a year at one theater. Lennon wasn't the only fan:
An actual "2001 Fan Club" has developed, with Mike Nichols, Mick Jagger, John Lennon ("I see it every week"), Franco Zeffirelli, Roman Polanski, Richard Lester, et cetera, represented. Where Did It Go Right, Chicago Daily News, ???1968, cited in The Making Of Kubrick's 2001, Jerome Agel, 1970.
John was so impressed that he considered having Kubrick direct the next Beatle movie, but the meeting went badly:
John - whose favorite movie at the time was 2001: A Space Odyssey - went so
far as to meet with Stanley Kubrick to interest him in the possibility of directing the Tolkien film [Lord of the Rings]. The interview, however, went poorly, and John came away wondering about how the man who'd directed 2001 could be so nowhere. Pete Shotton, John Lennon In My Life, p158
Kubrick's use of music in the film was very influential. It started a new career for Richard Strauss, rejuvenated Johann Strauss's fortunes and introduced a broad public to the avant garde music of Gyorgy Ligeti (who successfully sued the producers for using some of his music as the basis of distorted sound effects).
Alex North prepared a score for the film but it was not used (it has recently been restored and recorded). Instead, Kubrick used the pieces below.
Also Sprach Zarathustra Richard Strauss Ape music
The Blue Danube Johann Strauss Jr Moon trip
Gayane (Adagio) Khachaturian Jupiter approach
Requiem Ligeti Monolith music
Lux Aeterna, Gyorgy Ligeti, Moon bus
Atmospheres GyorgyLigeti, Light show flight
Information on AMM appearances at Yoko Ono's show and The Technicolor Dream provided by Tom (BlackMonk) of RMB. For a good discussion of AMM and Yoko Ono I recommend Tom's post "Who's Better" to RMB December 22, 1998. A simple deja search on "AMM" and "Yoko" will find it.
Bill Huelbig, from the alt.movies.kubrick newsgroup, provided most of the information regarding 2001 including the opening date in London ("I've got a 31-year-old page from the New York Times, which gives the London release date for 2001 as April 11, 1968, at the Casino Theater"). Thanks to RMB's Alley for locating the Shotton quote.