Seamus Milnes book takes as it's starting point the 1990 Daily Mirror/Cook Report "scoop" regarding Arthur Scargill and his National Union of Mineworkers associate Peter Heathfield. They were accused of embezzling monies to pay off their mortgages from donations made by Libyan Trade Unionists during the 1984-85 Miners Strike. The story led to Scargill and Heathfield being subjected to a number of lawsuits from their own Trade Unions executive, as well as a variety of Government bodies, investigations by the Inland Revenue and the Serious Fraud Office and left Scargills reputation in tatters. After months of official investigations, it turned out that the accusations were entirely false: one didn't have a mortgage, the other had paid his off out of his savings. Not only that, but the one person who had been involved in fraud (not counting the then Daily Mirror proprietor Robert Maxwell who enthusiastically supported the false claims) was the Daily Mirrors and the Cook Reports single source: Roger Windsor, the leading non-elected officer of the NUM through-out the Miners Strike of 1984-85. The information that Milne collated for this book strongly suggests that Roger Windsor was an informer, or agent, for the security services whose head of Trade Union espionage during the Miners Strike was Stella Rimmington, later to be the first female head of MI5.
Milne goes beyond debunking the smear campaign against Scargill and Heathfield to looking at a variety of other issues surrounding the Miners Strike. The activities of the Media, the Conservative Party, the right-wing of the Labour Party, MI5, a disparate bunch of right wing loons (not to be confused with MI5!), Special Branch and GCHQ during the strike, and in the subsequent destruction of the NUM and the British Coal industry are forensically scrutinized. The story that emerges is an ugly one that reveals the reality of power in Britain's "Democracy", the systematic emasculating of the Trade Union movement during the 1980's, the beginnings of what became New Labour, and the subversive and undemocratic nature of the Security Services role in British political life (as was again made clear with regard to the role of MI6 in the campaign for the Iraq War in 2002-03).
Milne's book is dense with detail, clearly written and essential to a full understanding of the Thatcher period in particular, and the British political scene in general. As an example of investigative journalism "The Enemy Within" is exceptional, and one that I can't recommend highly enough to anyone who is serious about the real story of what was possibly the most important event in post-war British history.