The Royalist army having disengaged and moved west, Browne was sent to capture Greenland House near Henley-on-Thames, under his original orders, and then moved to Reading. Ordered to join Waller at Abingdon-on-Thames, he objected that he had only 'three broken regiments of London auxiliaries, not above 800 in all' to hold Reading. In fact, he had fallen out with Waller and threatened to resign if forced to accept the latter's orders. In the end Waller left for London and Browne was put in command of the whole force at Abingdon, marching in with his brigade on 15 August. He and his troops were not involved in the Second Battle of Newbury in October, but as Governor of Abingdon, Browne kept up active skirmishing against the Royalist stronghold of Oxford during the winter. In the summer of 1645 he participated in the Second Siege of Oxford, and in September had to put down a serious clash between the garrison of Aylesbury and other Parliamentarian troops. He was again active in the final Third Siege of Oxford in 1646 and continued as Governor of Abingdon until the end of the First Civil War later that year. Political career Browne had been elected 'Recruiter' (replacement) Member of Parliament for the Buckinghamshire seat of Chipping Wycombe in October 1645, but had received a leave of absence so that he could continue his command (otherwise banned under the Self-denying Ordinance). In January 1647 he was one of the parliamentary commissioners to receive King Charles upon his handover by the Scots. He was with Charles at Holdenby House when the king was seized for the Army by Cornet George Joyce in July that year, an act that Browne vociferously opposed. He became an alderman of the City of London for Langbourn Ward on 29 June 1648 and was Sheriff of the City of London to 11 December 1649. As an opponent of the Army's policies, he was excluded from Parliament under Pride's Purge in December 1648, and was imprisoned for five years after being accused of conspiracy with the Scots. Browne was elected MP for City of London in 1656 for the Second Protectorate Parliament, but remained excluded. He was admitted to the Worshipful Company of Merchant Taylors on 10 December 1656. He was re-elected MP for the City of London in 1659 for the Third Protectorate Parliament and did take his seat until he was