I just came across a great New York Times piece on the mail service in the Victorian era. It's full of trivia: for example, did you know that in 1889 London, mail was delivered TWELVE TIMES A DAY? Read this:
In Victorian London, though service wasn't 24/7, it was close to 12/6. Home delivery routes would go by every house 12 times a day — yes, 12. In 1889, for example, the first delivery began about 7:30 a.m. and the last one at about 7:30 p.m. In major cities like Birmingham by the
Mailboxes are locked over here, that’s pretty much it. Nobody but you can take anything out of your mailbox:
there’s locked mail boxes here. like at apartments with a shared lobby. the owner just gets a key.
This, and the outgoing box is locked too. Anyone can put mail in, only the postie can take it out