No 6 - COLONEL - is a later version of the Ruston & Hornsby narrow gauge diesel locomotive, being type ‘16/20hp’ built in 1940 (works No. 202967) with a Ruston 2-cylinder 20hp engine.

It was supplied to the War Department, No. LOD 758097, although it saw little use with the army, being sold from store in 1968 to Steelbreaking & Dismantling Ltd of Chesterfield.

It was soon purchased by Chesterfield Corporation sewage works, where its career followed that of No. 7 - arriving at Yaxham in 1982.

The engine was overhauled in 2001, restoring the loco to full operational status.

Due to its easy to use controls, this loco is often seen in use on driving experience days.