The world's oldest underground railway outside London was built in 1886 and connected Liverpool and Birkenhead by tunnel under the Mersey. The original steam operation was converted in 1903 to electric 630 volt DC third rail equipment and Westinghouse rolling stock. In 1939 they were replaced by a fleet of Derby built LMS class 502 electric multiple units (EMUs) which operated for over 40 years. Following their farewell trip in October 1980, their historic significance encouraged the NRM to claim driving motor car 28361 and driving trailer 29896 for the National Collection There was no space for them at York and they were stored in the Steamport Museum at Derby Road, Southport. They were 'adopted' by the North West Group of FNRM and with volunteers from Steamport they undertook to restore and preserve both units. On 6 April 1986 they were in public service and operated again between Birkenhead North and Hoylake as part of the celebrations marking the centenary of the Mersey Railway company.
In 1988 they participated in the three day celebrations for the centenary of Lever Bros developments at Port Sunlight. The theme of the event was Transport over the Century and it attracted over 60000 visitors to the Transport Extravaganza. Over the three days the 502s operated shuttles between Rock Ferry and Hooton every 15 minutes and carried over 5000 passengers. Charles Lilley, the indefatigable leader of the NW Friends group, claimed then that 'it was the longest operation in time and mileage of any preserved EMU anywhere in the country' and so far that has never been challenged!