Original: However, by October 2007, the date for the first train entering service had slipped to January 2009 and the first train entered service on 21 July 2009, leaving the depot at 23:00 and forming train 277 leaving at 23:55 to.
Simplified: However, by October 2007 the date for the first train entering service had been moved to January 2009. The first train entered service on 21 July 2009, leaving Northumberland Park depot at 23:00 and forming train 277 leaving Seven Sisters at 23:55 to Brixton.