Simplify the following text for a Grade 9 native English-speaking person.
Original: The British Rail Class 11 was applied to a batch of diesel shunting locomotives built from April 1945 to December 1952 , based on a similar earlier batch built by the London , Midland and Scottish Railway ( LMS ) between 1939 and 1942 .
Simplified: The British Rail Class 11 is diesel shunting locomotive built from April 1945 to December 1952 . They are based on a similar earlier batch built by the London , Midland and Scottish Railway ( LMS ) between 1939 and 1942 .