Dictionary.net

• trans-pon'tin, adj. situated across a bridge, esp. belonging to the part of London on the Surrey side of the Thames, hence melodramatic from the tastes of the theatres there.

1908 - Chambers's Twentieth Century Dictionary of the English Language
By Thomas Davidson

• Of the part of London on Surrey side of Thames; cheaply melodramatic, like the plays formerly popular in t. theatres. [Latin]

1919 - The concise Oxford dictionary of current English
By Sir Augustus Henry