A factory producing which sort of antiquated machines was still in operation until this month?

Answer: Typewriters. According to an April 26 article in the Daily Mail, "Godrej and Boyce -- the last company left in the world that was still manufacturing typewriters -- has shut down its production plant in Mumbai, India, with just a few hundred machines left in stock." In case you're in the market for a brand new typewriter, be aware that the majority of the remaining typewriters are Arabic-language models.