THE Mersey Railway turned 133 years old on Sunday - making it the world's oldest underground railway outside London, but what's the story behind it?

Opening in 1886 with four stations; Green Lane, Birkenhead Central, Hamilton Square and James Street, the Mersey Railway used steam locomotives, becoming the first passenger railway system connecting Wirral to Liverpool.

Over a period of six years, the Mersey Railway line was extended to serve three more stations but became bankrupt in 1900 following a shift in passengers opting for ferry travel in order to get away from the polluted atmosphere in the underground tunnel due to the steam trains.

More than 20 motor cars were then handed to the Mersey Railway as it made the move the electric in 1903, these cars included first and third class carriages.

The carriages were maroon in colour with a white roof and Mersey Railway delicately painted in gold leaf near the top of the carriages.

Although the borough was given the green light to electrify its overground lines, it did not do so until 1936 so before this, passengers had to change at Birkenhead Park.

Mersey Railway remained independent in 1923 before being nationalised in 1948 like many other British railway companies at the time.

The line is still in use now but is used as part of the Wirral Line on the Merseyrail network.