Will Fly: The Hansard reporters take down, word for word, what is said in Parliament. They don't put a spin on it, alter it, comment on it, or misreport it. Hansard is not a newspaper - it is a transcript of the day in Parliament. Now, what is said may be anything - pearls of wisdom or absolute bollocks - but the reporters have NO choice in changing it. That is what makes it different from a conventional newspaper.
Will, what's supposed to happen is (from the Terms of Reference of Hansard as defined by a Commons Select Committee): "...which, though not strictly verbatim, is substantially the verbatim report with repetitions and redundancies omitted and with obvious mistakes (including grammatical mistakes) corrected, but which, on the other hand, leaves out nothing that adds to the meaning of the speech or illustrates the argument."
That's what's supposed to happen. In fact Hansard doesn't always report accurately what's been said. There have been several instances in the years since proceedings have been recorded when the official Hansard record has indeed been proved to have been edited in ways HAVE left out things "which have added to the meaning of the speech".
Also, if an MP does say something which is later proved to be inaccurate, then the "copy of record" of Hansard kept in the Commons library is amended to reflect this.
You're substantially correct, but there's a bit more to it!