Did MI5 and Special Branch allow an assassination plot against King Edward VIII to go ahead in July 1936?

On 16 July 1936 a man in a brown suit stepped from the crowd on London's Constitution Hill and pointed a loaded revolver at King Edward VIII. The monarch was moments from death. But MI5 and the Metropolitan Police Special Branch, tasked with royal protection, already knew all about this threat to the king's life.

The gunman, George McMahon, was a petty criminal with a history of involvement with the police in Glasgow and London. He was also an MI5 informant, providing valuable intelligence on Italian and possibly German espionage in Britain. McMahon had told his MI5 handler he was party to the conspiracy and had shown him the gun he always carried.

The information was passed to MI5's chief, Sir Vernon Kell, but nothing was done. Was the failure to act simply blundering on the part of the security services, or was something far more sinister involved? By the end of the year Edward had been forced to abdicate and live in exile, ostensibly because of his determination to marry the twice divorced American Wallis Simpson.

Using evidence from MI5 and police files at the National Archives, this book reaches explosive conclusions about the British Establishment's determination to remove Edward from the throne.