Apparently, the first guy to figure out that two-thirds of a Triumph Rocket III motor displaced roughly 1540cc decided that a Triumph cruiser with a twin of this displacement made a lot of sense. This rumor has been around for about as long as the Rocket III itself.
The rumor is getting stronger. We may well see a “big twin” from Triumph this Fall, with cruiser styling. Remember, in the cruiser category, Triumph jumps all the way from its small displacement twins (well under 1000cc) up to the giant 2294cc triple housed in the Rocket III. A bigger twin does make sense as a means of filling this displacement gap.