When I started planning the London Cosy Mysteries series with Millie Ravensworth (who in real life is two people: Heide Goody and Iain Grant), we knew we wanted to base each book at an iconic London landmark.

We had the idea of alternating between historical landmarks and modern ones: places that had been part of London’s landscape for centuries, versus sights built this century.

And our plan was to start with the most famous and frequently-visited of them all: Buckingham Palace.

Heide and Iain and I met up one afternoon in 2022. We tossed around potential locations for all six books on the series, mulled over a series arc which would give Diana an extra, more personal, mystery to solve over the course of the six books, and thought about where we would set book one.

The answer to that question was clear. We wanted a landmark that would be known to everyone who knew London, which we could visit as tourists, and which gave us the opportunity for some comedy.

The answer was Buckingham Palace.

Heide came up with a wonderful scene involving Diana revisiting the Palace in the course of informally investigating a murder that had taken place while she was leading a tour party around the building. A visit that would involve her accidentally leaving with a mischievous corgi in her bag.

So we started plotting our mystery. We had a cast of characters, a location, and a motive that related to one of the tour group members being the former owner of a company that manufactured a foodstuff with the coveted ‘by appointment to her Majesty the Queen’ label.

But then tragedy struck. The Queen died, and King Charles became the monarch.

Could we still write a book with references to the Queen? Could we still involve corgis? The dogs weren’t passed to the new King, after all - they became the property of the disgraced Prince Andrew. We certainly weren’t going to include him in a book.

And in addition, King Charles wasn’t as closely associated with Buckingham Palace as his mother was. He spent most of his adult life living at Kensington Palace, or at Highgrove. The comedic opportunities wouldn’t relate to plump little dogs but to comedy ears, and there’s far less mileage in those.

So we decided to rethink. What’s the other iconic London landmark, that everyone will instantly recognise on the cover of a book?

Why, the Houses of Parliament, of course.

So we met again, to discuss the new version of the book. There would be no corgis, no ‘by appointment to...’ food, no comedy ears.

Instead, we needed a premise that would find our heroes Diana and Zaf taking a tour group to the Palace of Westminster, along with a back story that would lead to a murder motive, and an unpleasant MP who may or may not turn out to be the killer, but who would certainly be the villain of the piece.

So we came up with the students of Foxton Grange Academy, in London on a tour arranged by their thoroughly sleazy MP, John Chapman-Moore. He manages to combine a thoroughly odious and entitled nature with a history that means the reader can’t quite be sure about any unacknowledged offspring he may or may not have. (I’m saying nothing about whether he was inspired by any real-life politicians.)

But the question remains. Chapman-Moore may be a thoroughly unpleasant human being. But is he a killer?

You’ll have to read the book to find out.