Greenwood & Batley's first successful venture into locomotive building occurred in July 1927, when five battery-electric narrow gauge locomotives were completed for Edmund Nuttall's Mersey Tunnel contract. These locomotives proved very reliable and a total of 31 G&B locomotives were used on the Mersey Tunnel construction. Other work developed rapidly. In 1928, flameproof locomotive were built for the Royal Navy and in 1929 the first export order was for seven, pantograph fitted locomotives for the Chinese Engineering and Mining Co Ltd.