sentences:  He was the younger brother of his colleague Joseph Armstrong, but thanks to the special requirements of the GWR at a time when it was split in two by the broad and standard gauges, the brothers were able to work largely independently of each other.George is best remembered for his 0-4-2 and 0-6-0 tank engines; these were long-lived, and even when life-expired they were replaced by Collett and Hawksworth with remarkably similar locomotives, the well-known 1400, 5700 and 1600 classes.George Armstrong was born on 5 April 1822.