GMT watches are the timepieces with the extra hand - and for good reason. As worldwide travel took off in the 1950s, time took on a new meaning. It began with the first commercial pilots of the jet-age who needed to tell the time both where they were and according to GMT. A watch with an extra hour hand was the answer. That additional hand moves at half the usual speed to follow the 24-hour clock and, set to GMT, avoids any confusion. It's an idea so simple that it's a wonder no-one had…
