Henry Porter was mentioned earlier - I'd second that recommendation though his last book, The Dying Light, I found a bit of a let down. The first four are cracking though (Brandenburg, A Spy's Life, Remembrance Day and Empire State).

I always find the Ludlum original books to be a great way to lose yourself in a bit of trash on a flight - they aren't going to win any literary prizes but score highly for escapism and neo-nazi plots to take over the world.... just remember the golden rules of reading Ludlums - never pick a book where there is a joint author (ie all the newer stuff remembering he died in 2001) or where the title is more than 3 words.