The other reviewer accurately describes the Screen One Hancock tv movie's account of what happened during this TV special but that is not what I saw.
For a long time, I thought only footage from one skit and the audio from the entire TV broadcast survived but I have since seen the entire TV broadcast
The main skit was Hancock struggling to do a scene from King Lear with another performer. In their frustration they swap roles from King to jester and back. The other performer either underperforms or upstages and Hancock reacts by doing the same. Its funny but not the best Hancock ever did. Hancock looked as though he lost alot of weight and not in a healthy way. He would become extremely sick the following year from his alcoholism. I think he first shows the signs of it in this special.
The rest of the show proved Hancock did follow a script because there are music cues he drops and a band picks them all up perfectly. Some of the cues happen during his impersonations which are usually considered the oldest routines he did. It would be impossible for anyone to pick up music cues without a script so those old routines he does were planned to be a part of the show all along. Hancock was mostly neurotic about remembering his lines anyway. That has more to do with a serious auto accident he suffered years earlier than alcoholism. Undoubtedly his lines were nearly everywhere for him to read while on stage if he needed them. Anyway, the show was humorous but not Hancock at his best.
Near the opening was a strange comic skit about how celebrities and show people are discovered he plays this character called "Bert Lust", a manufacturered star. I think he was making a comment on Fabian or a British version of Fabian.
The weakest part is his dramatic recitations which just didn't work at all. He put alot of energy in saying the lines but the humor wasn't there.
I would not classify this performance as a disaster but the director did Tony no favors. There is a cut away to the crowd during a brief break and the camera zoomed in squarely on a small collection of 5 empty seats and a dour faced man in a white suit sitting next to them. They showed those seats and that motionless man more than once. The crowd looks less than enthusiastic up front too but the applause are there.
I guess the goal for this show was to broadcast Hancock doing his standup routine and perhaps there never was a TV broadcast of that before so in that respect it was supposed to be "new". The show does prove there is a difference between a comic actor and a comedian.
As for the Screen One biopic. Its a mistake for any viewer to consider a biographical form of entertainment to be a viable source of factual information. The goal is to entertain, not to be accurate. Thats where artistic license comes in to play. If that biopic is to be believed more than reality, then you'd think Galton and Simpson quit Hancock instead of being fired by Hancock because their material was to centered on British humor and Hancock wanted to attract international audiences.
If this show was such a career destroying disaster as implied in that biopic, Hancock would not have been offered to do a series in the UK the following year which he was and did do. No footage beyond 180 seconds in length survives from that but Ive heard the show as being described as being better than the ATV shows he did in 1963.
I suspect other reasons for why Hancock left to do work in Australia. To get away from the tabloid frenzy surrounding his affair with John Le Mesurier's wife is one. To get away from the tabloid frenzy surrounding his near death in early 1967 from alcohol related illness is another. It certainly wasn't because the public rejected Hancock's talent in his homeland because they certainly had not.