#Arguably I didn't need to know quite as much as I researched about the UK's emergency response systems and how they would respond

[cycas]

...people can also ride horses, carry swords, have electricity, running water and flushing toilets in the real world too...?

Thing is, if I go to Asda on a horse, the first thing people are going to ask is 'why?' and this is not an unreasonable question to ask about a world you are spending time in. (There are places where turning up somewhere on a horse is still fairly normal, of course. It's Asda and the horse together that provokes questions, since Asda only exists in a world with tarmac and lorries.)

Running water and flushing toilets are old technologies, if your location is rich/organised enough, of course it can have them! (Though you might want to describe them a bit, so that I'm envisaging something that feels like an exciting fantasy world, rather than a private en suite bathroom at a Premier Inn.)

If you have electricity though, I am going to wonder where it's coming from and how it's generated and maintained, in a world that doesn't have trains or metalled roads or lorries or factories that are intimately connected with my ability to turn on a light.

I mean, it could be magic, but if so, that in itself is interesting and potentially spectacular. What demon is trapped in the generator? Why is it that magic here uses a centralised generation system rather than on-the-spot spells? Where do the metal wires for carrying the current around the place come from? Are electricians magicians? The characters will have some idea of the answers to all of that, and it will shape how they think about stuff, just as my ability to boil a kettle without having to make a fire first shapes mine.

Or are the generators powered in some other way? Generating energy to do work using wind and water is a very old way of doing things, adding electricity to them could work of course, but will be visible, exactly as our own power stations and power lines and maintenance trucks are visible.

If you have electricity, but no electricity generation system or power lines or mines, and the metalworking otherwise is at the level of 'local blacksmith', that can feel like you couldn't be bothered to think it out and have papered some horses and swords over the top of the world you live in, and then awkwardly rubbed out the bits that you don't feel fit your aesthetic.

I mean, you can leave it to the reader to imagine the river's electricity-mill and its twelve stalwart workers that keep the paddles turning and the lights on, and their feud with the flour-mills (in summer when the river's low, would you rather have brown-outs or wait a few weeks for your flour? demands Master Much the Miller) but the world will feel a richer place if you at least give them a hint about it.