I have been asked what gave me the idea to set my book in a world where the Roman Empire only ended two hundred years ago.

If you’ve ever seen any archaeology on television – and I’m thinking particularly of the days of Time Team – then anyone digging in a field in Britain finding a piece of Roman tesserae got very excited. It may only have been a small piece of stone, or tile, a cube about a centimetre across, but it was a sign that there once was a building there, which people lived in, with rooms in which hundreds of tesserae made up a complete mosaic floor.

That’s all we usually find in the UK. Odd traces that people once lived here, up to two thousand years ago.

And then I went to Tunisia. I visited several old Roman cities. In the car park of one, scattered amongst the sand and gravel, I found a number of tesserae. In Britain that car park would have been fenced off, with archaeologists on their knees, searching for remains of the buildings they came from.

In Tunisia, there was no need. Next to the car park was what was left of a complete Roman city, with many buildings still standing. The floors of the houses showed not just the odd little square tesserae, but whole complete tessellated floors.

Certainly, things are different there. The dry desert air preserves things. There is no population demand to go out into the desert and build a new town on top of the Roman remains, which is what has happened over the centuries in Britain.

However, looking at the buildings standing there, it was very easy to imagine that the Romans could still have been living there not that long ago. Perhaps they only left say two hundred years ago…

And so a spark was lit in my mind which caused me to ask, what would life be like now, if the Roman Empire had only ended fairly recently? And as I typed, a cube of Roman tesserae sat on my desk.*

*If you find one in this country, report it, it may be on the site of an undiscovered Roman building. However, the piece I picked up from that car park was already out of its proper context, just one of many scattered around the desert sands.