In 1681 Anglesey wrote A Letter from a Person of Honour in the Country, as a rejoinder to the earl of Castlehaven, who had published memoirs on the Irish rebellion defending the action of the Irish and the Roman Catholics.
The Earl of Anglesey (1682); A Letter of Remarks upon Jovian (1683); other works ascribed to him being The King's Right of Indulgence in Matters Spiritual.
Lord Anglesey married Elizabeth, daughter and co-heiress of Sir James Altham of Oxey, Hertfordshire, by whom, besides other children, he had James, who succeeded him, Altham, created Baron Altham, and Richard, afterwards 3rd Baron Altham.
The outcrops of these rocks succeed each other in order of age in roughly concentric belts, with the Archaean mass of the island of Anglesey as a centre, but the arrangement in detail is much disturbed and often very irregular.
In the bitter religious controversies of the time Anglesey showed great moderation and toleration.
In November 1660 by his father's death he had become Viscount Valentia and Baron Mountnorris in the Irish peerage, and on the 20th April 1661 he was created Baron Annesley of Newport Pagnell in Buckinghamshire and earl of Anglesey in the peerage of Great Britain.
Memoirs of Lord Anglesey were published by Sir P. Pett in 1693, but contain little biographical information and were repudiated as a mere imposture by Sir John Thompson (Lord Haversham), his son-in-law, in his preface to Lord Anglesey's State of the Government in 1694.
In so doing Anglesey was held by Ormonde to have censured his conduct and that of Charles I.