The article reviews "new documents" -- a term normally reserved for the secrets of government departments other than the BBC -- to find out what was going on behind the scenes while Python was on the air. Highlights:
The minutes state: "Aubrey Singer (the head of features group) said that he had found parts of this edition disgusting. Controller BBC1 said the programme was continually going over the edge of what was acceptable: this edition had contained two really awful sketches – the death sequence had been in appalling bad taste, while the treatment of the National Anthem had simply not been amusing.
"The Managing Director Television said it must be recognised that in the past the programme had contained dazzle and produced some very good things but this edition had been quite certainly over the edge and the producer Ian McNaughton had failed to refer the show to the BBC when he should have done.
"Stephen Hearst (the head of arts features) was critical of the fact that the values of the programme were so nihilistic and cruel… Bob Reid (the head of science features) felt the team seemed to wallow in the sadism of their humour. Controller BBC2 thought they also shied away from their responsibility. D.P. (the director of programmes) Television said the episode had been a sad end for the series. Bill Cotton (the head of light entertainment group) said it would be sad if the BBC lost the programme; the team seemed to have some sort of death wish."
Actually, most of the article isn't as much of a scoop as previously thought, because the sketch to which these comments refer -- about a cannibalistic undertaker -- was already known to have been extremely controversial at the BBC. The network was reluctant to approve the script in the first place, and finally agreed that the cast could do the sketch on condition that it ended with the studio audience expressing its disgust over the bad taste. Which, as network censorship goes, is pretty post-modern.
One thing I wasn't aware of is that John Cleese, who finally did leave after the third season (or "series," I should probably say), considered leaving after the first 13 episode run and had to be talked into returning for a second year.
Update: Thanks to a commenter for pointing out that this info is even older than I thought:
The memo you quote from was printed in Robert Hewison's "Monty Python: The Case Against" published in 1981.