The 04 is an ideal small diesel locomotive for your model railway, being used for shunting in local goods yards, shuttling coaches around major stations and hauling branchline goods trains in the 1950's and 60's. After being withdrawn from BR service these small shunters proved popular with industrial users and heritage railways.
These small diesel shunting locomotives took over from steam engines on light shunting and branch goods trains in the 1950's but became surplus in the 1960's as small yards were closed down. They did not vanish from the railway scene on withdraw from BR service however, many were sold to industrial users and heritage railways.