Has anyone ever come across the form -まする where -ます would be expected? I have just come across a sentence ending ...と存じまする.
My first thought was that る must be a particle, but I can't find any mention of it anywhere. Then I thought it could be a suru verb with the noun 存じま, but I can't find that as a noun in any dictionaries, and anyway in the context a plain する is very unlikely as it's someone addressing their social superior in a historical novel. Based on that, another possibility could be that it's a traditional polite suffix, but I can't find anything that would support that idea, and googling other verbs with the same ending does produce some results with e.g. ありまする, 食べまする, so I don't think it's an old-fashioned thing.
So basically, I'm stuck. It seems most likely that る is a particle, but if so what does it mean and why is it not in any dictionaries? Any ideas?