Given the task definition and input, reply with output. Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Context : The Midland Railway 156 Class was a class of 2-4-0 tender engines built at Derby Works between 1866--1874.
Answer : 1866
What year was the service entry date for Midland Railway 156 Class?