Use of The Honorific
The honorific is normally used only on the front of envelopes and other written documents: for example, The Rt. Hon. Ann Widdecombe was otherwise referred to simply as "Miss Widdecombe" before she left parliament at the 2010 election.
In the House of Commons, Members of Parliament refer to each other as "the honourable member for ... (then constituency)..." or "the right honourable member for ..." depending on whether or not they are Privy Councillors. Members usually refer to those in their own party as, "My (right) honourable friend", and to those in opposition parties as "the (right) honourable lady / gentleman".
Read more about this topic: The Right Honourable