Luke is a small engine, even for the Narrow Gauge Railway. When Luke arrived on Sodor, he hid out of shame believing that he caused an engine to fall into the sea. With Thomas' help, Luke learned the truth and was able to stop hiding.
Luke has an unquenchable enthusiasm for both his work and his fellow engines. He is based on the Kerr Stuart 0-4-0ST Wren Class 4256 built in 1922.