@izzythepush,
We were toured privately by the assistant of a MP (I'd attented party meetings in his constituency, he's an acquaintance of friends). This young lady wasn't allowed to make any further statements or explanations about the interior etc of both Houses, since this can only be done by officual tour guides. (She did, when they were out of sight).
She wasn't allowed - as assistant to the MP - to give us a tour through the Foreign and Commonwealth Office, where her boss was a Minister of State. So he did. after she left us at the security check-in.