The follow-up to the bestselling Courtiers, Power and the Palace lifts the lid on the intimate relationship between the sovereign and the government - a relationship that is at the heart of our constitution, but for all its importance is very poorly understood.

When Sir Keir Starmer visited Donald Trump in the White House and produced a letter from King Charles inviting the president for a second state visit, it was a gesture that spoke volumes about the continuing importance of the monarchy for Britain's international relations. It was also a vivid illustration of the relationship between Buckingham Palace and 10 Downing Street.

Power and the Palace lifts the lid on the mysterious power dynamic at the heart of the British state: the secretive and little understood relationship between the monarchy and the government. In vivid, page-turning prose, Valentine Low examines the extraordinary political life of Queen Victoria, who exerted her will in a way that no monarch has done since, the effect that had on her son Edward VII, and the turbulent and fascinating political times of George V. We are taken behind the scenes of the wartime meetings between George VI and Winston Churchill (the origin of the weekly audience) and discover how Elizabeth II played a crucial role in modernising - and saving - the monarchy.

At the heart of the book are the famous meetings between sovereign and prime minister. Low shows how, from Victoria and Benjamin Disraeli to Elizabeth II and Margaret Thatcher, personal chemistry proved just as important as the constitutional relationship.

Based on nearly 100 interviews with senior politicians, top civil servants, royal aides and constitutional experts, Power and the Palace rewrites our understanding of the political power of the monarchy.