Don't buy this assuming that the BBC material includes Howerd's history TW3 appearance which catapulted him back to stardom. It doesn't - and the BBC material is of variable comedic quality and sounds like it's from three separate shows, despite being presented as one track. The Establishment recording is, however, pure gold, showing Howerd at his best, well able to deal with the braying of Kenneth Williams and others in the very appreciative audience.
Whether or not it was an issue with licensing it's possible to understand why the TV comeback was not included - substantial portions, based on the extracts in documentaries I have heard, are the same as his Establishment act - but given its importance it would be worth listening to in its entirety, just as we are accustomed to alternative takes by jazz musicians etc. According to David Benson, who has heard the whole TW3 act, it tails off at the end - Howerd slightly outstays his welcome and loses the audience- but it would still be fascinating to hear.
Part, at least, of the BBC material is by Barry Took and Marty Feldman, and if you are familiar with Took's Laughter in the Air book on radio comedy you will recognise the opening BBC segment which is reproduced in the book. But the CD is well worth getting for the twenty odd minutes of the Establishment act which show a Howerd well able to tailor his comedy to the satirical needs of the day without being anything other than, well, Frankie Howerd.