Simplify the following text for a Grade 10 native English-speaking person.
Original: British Rail 's Class 27 comprised 69 diesel locomotives built by the Birmingham Railway Carriage and Wagon Company ( BRCW ) during 1961 and 1962 .
Simplified: British Rail 's Class 27 was a diesel locomotive built by the Birmingham Railway Carriage and Wagon Company ( BRCW ) during 1961 and 1962 .