Complex sentence: He then strikes with the end of his ceremonial staff (the Black Rod) three times on the closed doors of the Commons Chamber, and is admitted, and announces the command of the monarch for the attendance of the Commons.
Split into simpler sentences: He then strikes with the end of his ceremonial staff (the Black Rod) three times on the closed doors of the Commons Chamber. He is then admitted, and announces the command of the monarch for the attendance of the Commons.