Complex sentence: Rebuilding the station for the London Overground network began with site clearance in early 2005, and it was opened by the Mayor of London, Boris Johnson, on 27 April 2010.
Split into simpler sentences: Rebuilding the station for the London Overground network began with site clearance in early 2005. The station was opened by the Mayor of London, Boris Johnson, on 27 April 2010.