Sidmouth is a town on the English Channel in Devon, South West England, 14 miles southeast of Exeter. With a population of 12,569 i…Sidmouth is a town on the English Channel in Devon, South West England, 14 miles southeast of Exeter. With a population of 12,569 in 2011, it is a tourist resort and a gateway to the Jurassic Coast World Heritage Site. A large part of the town has been designated a conservation area.