- (simile) Very secure.
- 1874, John Camden Hotten, The Slang Dictionary: Etymological, Historical, and Anecdotal:
- an expression to satisfy a doubting person; "Oh! it's as safe as Houses," i.e., perfectly safe, apparently in allusion to the paying character of house property as an investment. It is said the phrase originated when the railway bubbles began to burst, and when people began to turn their attention to the more ancient forms of speculation, which though slow were sure.