The modern 'cosplayers' or as they want to call themselves, reenactors.
LOL doubt it. 20 years ago we were regularly "doing" medieval in York and don't remember any Roman re-enactors roaming about randomly in kit about apart from the odd one, bumped into on The Shambles once - and there was only one of him.
Few months back I was in a modern building in York, that has a massive picture window, waiting to do a Zoom talk in period costume - 1800s. And was walking about a bit, just before I went on. It was first storey but as I say, massive window. Realised there was a bunch of kids outside, staring open-mouthed up at the window where I was... (Kids' playground just outside).
There were two of us in this utetrly modern building but dressed as 1800 people so we decided to mess with their heads...
Someone had to bring a couple of the kids up, to prove we weren't ghosts (and walked in with them during my talk which pissed me right off). But there may well now be some of those outside-kids who are convinced they saw an 1800s' farmer's wife and a strange man in a top hat, in York, a few months back...
But lol, no. Have walked right through town in various incarnations - mainly 15thC - and never got a second glance. Everyone's used to seeing Vikings at pedestrian crossings and my mate who did Anglo Saxons and 1780s, regularly went shopping wearing her 18thC cloak in winter - never got the side-eye, even.
I'm still convinced that man we regularly see in complete 1950s' office worker get up on Goodramgate has to not be real, though! (No, actually he's very solid indeed).
What I'm trying to say is - re-enactors/living history people tend to know eachother, quite often (at least, they all know my other half, I never recognise anyone!) so we'd hear on the grapevine if a bunch of Romans were in town and we were very active at that time, and I don't recall it.
ETA: Also if they're actual battle re-enactors, they have to be well insured with public liability insurance to do what they do - so would be unlikely to be fighting with weapons even at dawn when nobody was about, least of all if in the centre of a city.