Ainsdale, mentioned in the Doomesday Book as Einuluesdel, Scandanavian for "Valley of a man called Einulfr".
The Battle of Brunanburgh in 937 brought changes to the area. It was no longer part of the Kingdom of Northubria, but part of Mercia.
Ainsdale doesn't appear on maps until the Yates map of 1786. In the 16th and 17th centuries the Halsall family of Halsall owned Ainsdale, but it was mortgaged to Robert Blundell of Ince by "Bad Sir Cuthbert" Halsall in 1631. In 1632, Sir Cuthbert died, and his widow was given a chance to pay off the debt. She couldn't, so in 1634 Robert Blundell took it on. Ainsdale was owned by the Blundell family into the 1800's. In 1837, Charles Blundell had no children so he left the town to a distant relative of a nephew, Thomas Weld, who changed his named to Thomas Weld-Blundell.
Times being what they were, and the government changing from Protestatism and Catholicism and back again, often put the Blundell family, who were Roman Catholics in the position of having to pay fines or even having the property taken away from them. But, friends controlling most of the justice system kept it from being even worse.
In 1848, the railway changed the small village and within a 140 year range the poplulation went from just under 200 to almost 16,000 in 1974 when Ainsdale changed from being part of Lancashire to being part of the Metroplitan Borough of Sefton in the newly created county of Merseyside.
More history of Ainsdale:-http://www.merseyworld.com/stjohns/history.html