Clock bag

A clock bag is a bag used in bookmaking with a lock and a built-in clock, intended to prevent fraud by proving the bets inside had been placed before a sporting event had started.^[1][2][3] The bets, or "lines", inside would often be "rolled in bundles each marked by a pseudonym".^[4]

Clock bags were in regular use in illegal gambling starting during the 1920s.^[5] In Glasgow during the 1930s, runners would collect bets in clock bags and then telephone bookmakers for the outcomes. This was a common practice called "shovel betting".^[1]

It has been speculated that clock bags may have originated around pigeon racing.^[5]