Just a few notes on Halton Castle.
Although Pricess Aethelflaed (various spellings of her name appear), King Alfred's daughter, built a Saxon fortification at Runcorn there is no visible evidence of it, or its site, today. However the Normans did build a castle on the hill at nearby Halton, and remains of this are still visible. The Barons of Halton were the next most powerful people in this area after the Earls of Chester, and were given the title of "Constable of Cheshire". Over a period of some 250 years from 1080 A.D. they became Earls of Lincoln, Earls of Lancaster, Dukes of Lancaster, and finally King (Henry 4th).
At that point the Barony of Halton came to an end. The castle was used as a prison and during the civil war as a Royalist base, but was destroyed on being captured. Today only a few walls remain, many restored. The site is being run by the Norton Priory Museum Trust on behalf of the Halton Council, who hold it from the Duchy of Lancaster.