Alexander Radclyffe, the eldest son and heir of Sir John, was born at Hope about 1401. The inquisitions on the deaths of his father and uncles show an extraordinary disparity in the recorded age at these periods, but the above date seems to be the most acceptable as the date of his birth. Alexander had received from his father a moiety of Flixton on his marriage to Agnes Harrington, and Shoresworth also seems to have been a portion of the dowry. By his marriage to the daughter of Sir William Harrington of Hornby Castle Alexander further enriched the noble blood of his already illustrious line. Through her mother, Margaret Neville of Hornby, Agnes was descended from King Ethelred, through his daughter, Elgiva, who was married to Uchtred, Earl of Northumberland. Their descendant, Robert Fitz-Maldred, Lord of Raby, married Isabel, daughter of Geoffrey, Lord Neville, from whom descended Sir Robert Neville of Hornby, who married Dorothy, daughter of William de la Pole. Margaret Neville was the daughter of this marriage. On the paternal side, Agnes traced her descent from Alice le Fleming, sister and heir of Michael, Lord of Aldingham, and wife of Richard de Cauncefield. Their daughter, Agnes, married Sir Robert Harrington, and had a son, Robert, who married Margaret, daughter and heir of Sir Thomas Banastre, Baron of Newton. Their son, Sir Nicholas Harrington, married Jane, the heir of Sir Thomas English of Wolfege, and Sir William Harrington, father of Agnes, was their eldest son, Lord of Hornby Castle in right of his wife
The Radclyffes of Ordsall had by this time advanced to become one of the most influential houses in the county, and in 1455 Sir Alexander was a knight of the shire. Family feuds were still rampant, especially amongst the younger sons of neighbouring proprietors, where the motive of the quarrel might be trivial, but was sufficient to excite the passions and prejudices of the young hotheads, in whom the ascendancy of military habits and the rough-and-tumble of education of the time encouraged a disposition to satisfy their honour and settle their grievances by taking the law into their own hands. One of these disputes between local Montagues and Capulets came to a head on the Monday after Low Sunday in the year 1444. The Booths of Barton were a powerful landed family, the bounds of whose estates ran partly with the Radclyffe lands. On the day in question John Radclyffe, his brother High, and a party of their friends, including their uncle, Peter Radclyffe, were hunting in the Wheaste, which was part of the royal forest adjacent to their estates. As they approached the manor house of Little Bolton, their way was challenged by William Gawen, the lord of the manor, who had summoned to his support Sir Thomas Booth of Barton, with his sons, Nicholas and Henry, and a strong force of armed retainers. In the fracas that ensued John Radclyffe was slain by one of the Booths, Hugh Radclyffe died at the hands of Lawrence Hyde, of the Barton faction, and the two others of the Radclyffe party, Ralph Oldham and Nicholas Johnson, were also killed. Peter Radclyffe was responsible for the death of Peter Cowapp of Barton. All the delinquents were brought to trial but were acquitted. Subsequently, Sir Alexander again proceeded against the Booths at a later assize, when Henry and Nicholas Booth received sentence of outlawry. In 1455 the Wars of the Roses began with the first Battle of St. Albans, and the Radclyffes were prominent in their support of the Lancastrian cause. At the battle of Wakefield in 1640 Lady Agnes Radclyffe lost her brother, Sir Thomas Harrington of Hornby, and her nephew, Sir John Harrington, who both fell fighting on the King's side. Sir Alexander himself died in 1475, on the 20th July. Lady Agnes survived him fifteen years. They had issue of five sons and three daughters