Where does the British government store its murkiest secrets?

In 1983 I was part of a cast that performed a play in Parkhurst Prison. The 'dirty protests' were taking part in the adjoining Albany Prison; the officers in Parkhurst said our play, the first live entertainment in the prison for over a decade, had headed off similar protests in their prison. Apparently some of the most high profile and feared inmates, including members of the Kray gang, had constructed the set and were determined that nothing would get in the way of the production. After the successful performance, the grateful prison officers took us for a drink, during which they gossiped that there was an inmate in Parkhurst who had burgled the flat of a prominent government minister and taken away a stash of child pronography. The officers alleged that this prisoner, having been caught trying to sell the material, was serving a shorter sentence in return for keeping his mouth shut.

Soon after 1983 the minister resigned suddenly. Many years later, following the collapse of a police enquiry into this former minister, there was a vigorous attempt to rehabilitate his reputation.

If it ever existed, the government probably still holds the damning evidence burgled from the minister's flat. They almost cetainly hold truckloads of other sensational material on other important figures from the past and present.

It got me thinking: where would they store such sensitive evidence? How could it be kept fully leak-proof? If someone wanted to rehabilitate a figure compromised by material held by the government, how would they go about destroying that evidence?

This was the germ that inspired my novel 'Shadow of a Shadow', to be published by the Book Guild in June 2023. The answer given in the novel is that all such intelligence is stored in analogue form in an archive called H11, deep below MI5's London HQ, Thames House. [H11 is actually the name of the classroom I taught in for thirty years].

But what sort of MI5 employee gets to spend years of their career cooped up underground, observing the strictest security rules imaginable, guarding the most toxic secrets that no one is ever likely to use? As one member of the H11 team wryly observes, 'We've all been sent to the naughty step for something.' How would such a job affect someone's sanity? And if one of the team was murdered, who would be unpopular enough to be sent below ground to investigate it?

Step forward Lydia twomey, 'modern suffragette' and scourge of the MI5 old boy network.