While his call to the Bar on 7 November 1661 would normally herald the start of a legal career, by this point Eyre had already been returned as MP for Downton.
Joining the opposition under Lord Warton, Eyre laid aside the debate on the Thirty-Nine Articles before abandoning his seat at the 1661 general election in favour of Gilbert Raleigh.
Following the Glorious Revolution and James II's flight, Eyre was returned for the Salisbury Parliamentary constituency, playing a role in drafting the Bill of Rights 1689; he is thought to be the author of Reflections upon the late great revolution: written by a lay-hand in the country for the satisfaction of some neighbours.
[1] On 8 May 1689, he was made a Justice of the King's Bench and a Serjeant-at-Law,[2] receiving a knighthood soon afterwards; he held this position "with great credit" until his death on 2 June 1695.
[1] A painting of Giles Eyre by Thomas Hudson (1701–1779) was formally in the possession of Cider House Galleries Ltd.