Birkenhead (; ) is a town in the Metropolitan Borough of Wirral, Merseyside, England; historically, it was part of Cheshire until 1974. The town is on the Wirral Peninsula, along the south bank of the River Mersey, opposite Liverpool. At the 2011 census, it had a population of 88,818. Birkenhead Priory and the Mersey Ferry were established in the 12th century. In the 19th century, Birkenhead expanded greatly as a consequence of the Industrial Revolution. Birkenhead Park and Hamilton Square were laid out as well as the first street tramway in Britain. The Mersey Railway connected Birkenhead and Liverpool with the world's first tunnel beneath a tidal estuary; the shipbuilding firm Cammell Laird and a seaport were established. In the second half of the 20th century, the town suffered a significant period of decline, with containerisation causing a reduction in port activity. The Wirral Waters development is planned to regenerate much of the dockland. Toponymy The name Birkenhead probably means "headland overgrown with birch", from the Old English meaning birch tree, of which many once grew on the headland which jutted into the river at Woodside. The name is not derived from the Birket, a stream which enters the Mersey between Birkenhead and Seacombe. The Birket is a later name which was introduced by Ordnance Survey. History Medieval period The earliest records state that the Mersey ferry began operating from Birkenhead in 1150, when Benedictine monks under the leadership of Hamon de Mascy built a priory there. The priory was visited in 1275 and 1277 by Edward I. In a royal charter of 13 April 1330, Edward III granted the priory further rights. 19th century Distanced from the Industrial Revolution in Liverpool by the physical barrier of the River Mersey, Birkenhead retained its agricultural status until the advent of steam ferry services. In 1817 a steam ferry service started from Liverpool to Tranmere and in 1822 the paddle steamer, Royal Mail, began operation between Liverpool and Woodside. Shipbuilding started in 1829. An ironworks was established by William Laird in 1824, and he was joined by his son John in 1828. The business eventually became the shipbuilder Cammell Laird. Notable naval vessels built at Birkenhead include HMS Achilles, , , , , , , the pioneer submarine , (which sank in Liverpool Bay during sea trials, and was refloated and commissioned as HMS Thunderbolt, only to be lost to enemy action