I'd imagine that with the publishing world under increasing cost pressure, editing is an area that ends up being squeezed. Errors in a non fiction work are annoying, but the question is: how annoying? In the context of an autobiography, where you're in your armchair listening to an old man reminisce (sorry, Mr Newey), insignificant errors in background information that's not central to the author's story doesn't bother me too much.
As for the statements that are central, well, they're still only one man's view of things. Much as I love autobiographies, I trust them less than biographies. They're not a good source of information about the occasions when the author is seen by others as wrong or unreasonable.
In that context, Newey's book comes across as one of the more honest, as well as one of the most enjoyable. Tony Southgate's is also a great read, Harry Weslake's is best ignored.