The Earl of Essex's Regiment of Foot (known as the Lord General's Regiment) was naturally the first and foremost regiment of foot raised for the Earl of Essex's Army (known as "Olde Robin's Foote"), and fought in most engagements of the army. The regiment was reputed to be one of the better ones of the Army of Parliament, and naturally was the counterpart to the King's Lifeguard of Foot.
At Edgehill the regiment fought valiantly against the King's Lifeguard of Foot and Duke of York's Regiment of Foot, to cover the rout of four other regiments of the Earl of Essex's Army. After the battle the regiment was naturally one of those retained in the Earl of Essex's Army, when others, as a result of severe casualties, were reduced to bring regiments up to strength.
From Jan-Apr. 1643, the regiment (along with the army) was decimated by disease while in the Thames Valley & Aylesbury areas, and besieging Reading. On 1 February, 1644, Parliament realized the army needed complete reorganization and recruitment to oppose the King's Army. The regiment was naturally retained, rather then being reduced, but with only 8 companies.
The regiment, along with the rest of "Olde Robin's Foote", surrendered unconditionally to the King at Lostwithel on September 2nd (the Earl of Essex escaped the night before with some of his staff via fishing boat). The troops were not plundered by the Royalists on the King's command, but the local people stripped them to the skin once they were free of their Royalist guards on their way to Plymouth.
On September 19th new clothes were sent to the army, consisting of coats, breeches, stockings, shoes, caps, snapsacks and all arms. From arms issued at this time, it seems that the Earl of Essex' s Regiment of Foot (as well as the rest of the army) had a pike to musket ratio of 1 to 6. During this uniform issue no mention of tawny-orange coats is known, instead red and grey being more likely.