I’ve just finishing filming a three-part series on the Tower of London. Made by production company True North, it will air on National Geographic in April 2012. My co-presenter was the brilliant Joe Crowley.

We explored some of the best and most fascinating stories associated with the Tower of London: from Anne Boleyn’s alleged adultery, to James Scott, Duke of Monmouth’s botched execution in 1685, and from Father John Gerard’s daring escape from the Tower in 1597, to the storming of the Tower by a huge mob of peasants in 1381. In each case we were challenging some of our basic assumptions about the Tower, and learning a lot along the way: even in areas where we thought we knew it all already!

I met a wonderful array of experts, including a former spy and a Home Office pathologist, explored the Tower’s defences, and got to look at some beautiful historical documents. I even spoke to a relative of the last person to be executed at the Tower (in 1941!) which was immensely moving. Joe learnt how to make an executioner’s axe, shot targets in a firing range, and scaled Tower 42! Clambering into priest holes, going to where Robert Catesby and the other Gunpowder Plots had their final shoot-out, and seeing the farmer’s field where German spy, Josef Jakobs, landed in Cambridgeshire, all brought home new perspectives on some familiar, and some unfamiliar, material.

Many of the nine cases we investigated fell within my area of specialism – the Tudors and Stuarts – so filming the series was a particular joy to me. Some of the documents that fascinated me most were letters from Edward VI, Lady Jane Grey (whom I’m convinced should henceforth be called Jane I) and Mary I in the crisis of July 1553. I also enjoyed reading the post-mortem report on Lady Arbella Stuart’s corpse in 1615, and several Acts of Attainder under Henry VIII, chiefly those against Thomas Cromwell and Katherine Howard.

I also read the oldest book I think I’ve ever held: a fourteenth-century account of Simon of Sudbury, Archbishop of Canterbury’s death by Thomas Walsingham, kept at the College of Arms. (It was great that my palaeographic skills came in so useful, but I admit that the one thing I wasn’t expecting to come away from the series with was a conviction that I must improve my Latin!)

It was also particularly amazing to be let into the Acts Room at the Houses of Parliament: every roll is an Act of Parliament passed between 1497 and 1850! I could have stayed in there for a very long time.

Joe and I researched different aspects of each story and then came back to share our perspectives, which occasionally led to some heated debates. I hope the series will be as fun and informative to watch as it was to make!