He Who Dares: Downing Street Siege (2014) online

Following his heroic actions in He Who Dares, Christopher Lowe is summoned to 10 Downing Street to be dishonourably discharged from the SAS for disobeying a direct order, despite the fact his actions saved the Prime Minister's only daughter. However, when kidnapper, Alexander Holt, escapes from prison and plots the kidnap of the PM, there's only one man to turn to.