The new-look House of Commons will today take to the green benches for the first time since the General Election.
The re-shaped political landscape will be on physical display as, after 13 years on the Government benches, Labour MPs make way for the Conservatives and Liberal Democrats.
And more than a third of MPs - 226 of the new 650-seat chamber - will be fresh faces in Parliament after the expenses scandal prompted the biggest exodus in living memory.
Proceedings will begin this afternoon with the Commons being ceremonially summoned to the House of Lords, where the Lower House will be instructed to elect a speaker.
As the new parliament commences, MPs will take their seats simply to decide whether or not John Bercow should be kept on as Speaker.
If they decide that he should, the swearing in of all MPs will start tomorrow afternoon.
If they decide to elect a new speaker, that process will take place tomorrow and MPs will have to wait until Thursday morning before filing in to take the oath of allegiance.
But today will be the first time that the Tories will sit to the right of the speaker's chair since 1997. It is many decades since the old Liberal Party sat on that side.
Prime Minister David Cameron has only ever sat on the Opposition benches, having entered the Commons in 2001.
The exact shape and dynamic of the new Commons - with no "third party" because the Liberal Democrats have joined the Government - remains to be seen.
The election of the Speaker is the only business MPs are allowed to conduct before they have taken the oath - or made the non-religious solemn affirmation - to the Queen.
The Speaker is the first MP to take the oath, followed by Father of the House Sir Peter Tapsell, the Cabinet, the shadow cabinet and other privy counsellors and ministers.
Backbench MPs are taken in order of seniority, based on length of service in the Commons. The procedure is expected to run into next week.
MPs can choose to swear on either the New Testament, the Old Testament (in English or Hebrew), the Koran, the Granth, the Welsh Bible or the Gaelic Bible.Reuse content