What years do the professor layton games take place in?

I would like to know the time period of the games.What years do the professor layton games take place in?
It's previously been announced on Hershel Layton's Twitter that the London setting is between the years 1956 and 1967



Unlike the speculative guesses that most players come up with when asked this question, this is based on when key features of London, as seen in the games, started and finished in real life



While this period in London's history is the setting, the games are not grounded in reality and feature stories that are not yet possible in the modern worldWhat years do the professor layton games take place in?
It looks like the 1800's or the 1900's, although I think they took place in their own time (ie; Not a specific date, just some date that isn't known, thus becoming it's own date.)