A contemporary Gilbert Burnet later described him as "...the roughest and boldest speaker in the House, [with]] the language and phrases of a carrier...he spoke always with much life and heat, but judgment was not his talent.

With the help of Sir Arthur Haselrig, Birch was commissioned in the army commanded by William Waller, and quickly proved an energetic and courageous officer.

[5] Birch recovered in time to fight at Cheriton in March 1644, a Parliamentarian success that forced Charles I onto the defensive in South East England.

[10] However, victory resulted in increasingly bitter disputes over the post-war political settlement between radicals within the New Model like Oliver Cromwell, and the moderate party in Parliament, which included his former commander William Waller, and Denzil Holles.

[14] Birch met with Charles II prior to the Battle of Worcester in September 1651 but avoided direct participation, possibly due to the influence of his cousin Thomas, who remained loyal to the Protectorate.

After the Stuart Restoration in 1660, he was removed as High Steward of Leominster, and forced to sell his lands back to the church, ending his influence in the area.

[13] Although he never held high political office, Birch sat on numerous committees, especially those connected to public spending and taxes, where he proved a relentless and astute auditor.

His presence on the committee to review naval expenditure after the Second Anglo-Dutch War brought him into contact with Pepys, who noted he "do take it upon him to defend us, and do mightily do me right in all his discourse".

[16] The Act of Uniformity 1662 expelled Presbyterians from the Church of England, among them being John, and his brother Samuel, who was evicted from his parish of Bampton, Oxfordshire as a result.

[12] His youngest daughter, Sarah, inherited Garnstone, on condition she marry her cousin, another John Birch; he held the Weobley seat almost continuously from 1701, until his death in 1735.