The British Rail Class 777 Metro is a class of electric multiple unit passenger trains currently under construction by Swiss rolling stock manufacturer Stadler Rail, to be used on the Merseyrail network in the Liverpool City Region and the Wirral Peninsula. Ordered in 2016, construction of the units began in 2018. The trains are expected to enter service in 2022. The Class 777 will replace Merseyrail's current Class 507 and Class 508 units, which were built between 1978 and 1980.