Walter Nelson’s The Siege of Buckingham Palace (1979) was retitled for the UK as The Minstrel Code. An alliance of international terrorists infiltrate Buckingham Palace (in a Fortnum & Mason’s van) and hold The Queen hostage!
The government, police and the army scramble to identify the terrorists and attempt a rescue. But how?
This is well-researched, but not always realistic. The stock characters and lack of humour make this a very dry procedural. As with many siege stories, most of the plot is the build up to the plan of action.
The Queen isn’t even a character, barely mentioned and no real part of the plot, except as the one hostage the country can’t afford to lose.