The Civil Wars, despite their importance in British history, tend to be little discussed – certainly in comparison to, say, the Tudor or Victorian eras. Why do you think that is – is the conflict viewed as too complicated, or stemming from obscure religious and political disagreements which seem remote to us, for example?

I think that’s often the perception – that it’s too hard, too obscure – when, really, it’s just unfamiliar. But this was a time of climate change, puritanism, populism, statue wars and a polarising new media. It’s the most resonant period in our history.

If it was more central to the curriculum, or if we had a big Ken Burns style documentary series on it, or a great movie, or a Hamilton-style musical, the plates would shift, I suspect. (On the latter, watch this space as the brilliant writer Thabo Stuck is currently developing a Grime musical based on the 50 days before the king left London and it’s brilliant, just what we need to get young people into the subject).

You’re an expert on the religious struggles of the early modern period and have previously demonstrated that it was a more complicated issue than Catholics versus Protestants. Are there any misconceptions about the period’s faiths that you sought to counter?

Well, first off, the Civil War was largely a fight over different versions of Protestantism rather than Catholic vs Protestant. Even at Basing House, which was seen as a ‘popish’ garrison, around half the defenders were Protestant.

But really I just want to stress that the religious spectrum was very wide. Some sources, particularly the newsbooks, reflect hyper-polarisation (not unlike today when you get extreme views on panel shows). It’s easy to lose sight of the moderates, but there were lots of them, petitioning for peace when the war began. The tragedy was that their voices were drowned out by the ‘fiery spirits’ on both sides, so the violence escalated.

You approach the Civil Wars from an impartial narrative perspective. Did you find yourself drawn, though, to any particular figures? In other words, did you have a favourite, particularly amongst the defenders of Basing House?

Yes, an apothecary called Thomas Johnson, who had a shop on Snow Hill, near Smithfield. He sold the first (recorded) bananas in England and was also a plant-hunter. He travelled all over the country taking cuttings from fields and roadsides, even up Mount Snowdon. His dream was to write the first comprehensive flora of England and Wales and you get a wonderful sense, reading his notes, of this unstoppable energy. He encapsulates for me what Vasily Grossman called ‘the furious joy of life itself’. Then the war came and his world, like so many others, was turned upside down.

One of the things that the book brings vividly to life is the harried, febrile atmosphere which prevailed in London before and during the wars, and which spilled over in the rest of the British Isles. To what extent do you think everyday people in the other parts of Britain experienced the conflicts, and how did they view them?

Parliament forces overwhelm the Basing House defenders.

Some parts of East Anglia and the south-east weren’t too badly affected in terms of destruction of property, but if you lived near a garrison, in Faringdon, for example, your town could be reduced to ‘ashes and rubbage’.

In terms of loss of life, the figure was greater, proportionately, than for the First World War. We also have to consider the knock-on effects – absent husbands, higher taxes, rising prices, trade slumps, disease, looting, plunder. In some parts of the country, especially in the south-west, people were so fed up with depredations from both sides that they formed local associations of ‘Clubmen’ to defend their farms and families against all comers.

Basing House is central to the text. What kind of atmosphere did you find amongst the ruins?

It can be quite eerie, especially if you’re there alone when the mist rises from the river. I haven’t seen any ghosts, but the locals have.

One of the things that comes through very clearly in the book is the texture of life under siege during the wars. I’m always interested in how people thought of themselves through their lives, decisions, and actions. Do you feel that the men and women in Basing House were aware of their posterity, or do you get the impression that they were simply surviving, day to day, unsure how history would view them?

I think that during the most intense phase of the siege, when they were reduced to eating dogs, cats and rats, and having to sneak out at night to cut grass for their horses, and had to deal with smallpox and were under heavy mortar fire, it was simply a matter of making it to the end of the day.

I was intrigued by your noting that the house had become identified with the Stuarts prior to the Caroline era. Yet it had entertained each of the Tudor monarchs, as well as King James, and Anna of Denmark. Do you think it stood – to parliamentarians – as a symbol of monarchical, as well as papistical, excess?

Yes, definitely, but the two went hand in hand, so the house was depicted as a ‘limb of Babylon’. It was massive and lavishly furnished. The Marquess of Winchester’s bed there was reputedly worth £13,000. And some of the house’s defenders were prominently associated with the king and court – royal chaplains, artists, actors and the architect Inigo Jones who had turned Charles’s exalted sense of majesty into an intoxicating imperial aesthetic.

One of the consistent elements of the text is the tension between Winchester and Rawdon, both royalist defenders but one Catholic and one Protestant. Do you think this internecine conflict weakened the besieged within Basing House?

Absolutely. Morale is everything. Rawdon’s regiment was on the point of mutiny after the long summer blockade of 1644. Rawdon and Winchester were chalk and cheese in every respect, not just religion. I found it interesting that the infighting, as with other aspects of the siege, reflected the wider war, so Basing House serves as a microcosm.

One intriguing aspect of the book is the amount of spying going on. Could you tell us a little about the life of a spy – male or female – during the wars?

They had to be very crafty – one hid messages in a hollowed-out walking stick – but it was rarely glamorous and always risky. One of Basing House’s agents, a porter from Smithfield called Tobias Baisly, was caught and hanged in London. Another royalist spy, Katherine de Luke, was whipped and tortured with lit matches. High-ranking royalists later vouched that she was ‘a great sufferer for her loyalty and service’.

Charles I remains mainly a background figure in the book, as he was not present at Basing House. What are your thoughts on this controversial man and king?

I don’t think he was a bloodthirsty tyrant, but he was blinkered, stubborn, duplicitous and weak at a time when the three kingdoms under his rule needed flexible, lateral thinking, integrity and strength. He also had terrible instincts and very bad luck.

You draw on a wide variety of sources. Are there any from this period you think have been neglected and which deserve more attention?

The livery company archives – Clothworkers, Goldsmiths, Apothecaries etc. – are a bit of a trove. Local county record offices, too, can have really interesting archives and it’s always worth keeping an eye out for recent acquisitions or bequests.  The notebooks of the astrologer William Lily – now in the Bodleian Library, Oxford – provide an amazing mirror into the hopes and anxieties of the age.

But if I had to name just one neglected source, which really made my heart race, it would be a little book written by a clergyman who was probably at Basing House. It’s called Meditations upon a Seige [sic] and it takes you into the bowels of a siege like no other source I’ve read.

In researching the book, did you come upon anything that surprised you?

Almost every day. But the biggest revelation was at the end, when I discovered that 100 or so defenders, who had hidden in vaults and priest-holes when the house was stormed, did not actually burn to death in the subsequent fire, as has always been stated, but survived and re-emerged two days later.

Finally, what are you planning next?

I’m pondering two very different books – one on my favourite subject, early modern London, the other on my grandmother whose mother was from Kharkiv and father from Ekaterinoslav (modern-day Dnipro). She fled the revolution as a teenager and met my English grandfather on a railway siding on the journey south to Odessa. He was a Foreign Office man and had all sorts of interesting postings. He rehoused refugees for the League of Nations, worked as press attaché in Belgrade and was involved in the effort to get the Americans into the Second World War. I need to explore both subjects further before I decide.

Jessie Childs is a writer and historian and author of The Siege of Loyalty House: A Civil War Story.

Steven Veerapen is an academic, novelist. His new book is Of Blood Descended.