(2012, Jessica Chastain, Jason Clarke, Jennifer Ehle)

A sequence set in London depicting the lead up to the bus bombing on 7th July 2005 features several London buses. I don't believe the film makers intended this to be a depiction of a single vehicle - in any even it isn't.
First seen (from another bus) is Abellio London 9839 (KN52NEJ), a 2003 Dennis Trident/Alexander ALX400 new to Armchair. (Abellio did not begin operation in London until 2009):

Seen next from another bus are two Alexander Dennis E400s, the rear of which is Metroline TE672, a bus new at the end of 2005:

Passing is a Metroline Wright Gemini 2 bodied Volvo B9TL:

….and the bus we're travelling on is revealed in a shop window as Sullivan Buses PDL26 (PJ02PZZ), a 2002 Dennis Trident/Plaxton President new to London General, shown as working route 30:

Lastly we see an Arriva Wright Gemini bodied 'decker, which is depicted moving behind a tree before a massive explosion:

This is followed by news footage of Stagecoach London 17758 (LX03BUF), the Dennis Trident/Alexander destroyed by a terrorist bomb while operating on route 30.