On 10th November the King marched from Maidenhead to Colnbrook, whilst, according the Venetian Ambassador, parliamentary London was in a “great stir“ at the prospect of a royalist attack.  With the King’s army deployed in a wide area to the west of London, including at Colnbrook, Egham, Ashford and Windsor, parliament sent members of both houses of parliament to treat with the King, meeting him in Colnbrook on 11th November.  The King agreed to talks at Windsor and the message was received “by both Houses with a great deal of joy” on 12th November.

Parliament believed the King had promised to enter into peace negotiations and not attack London, but by early on the morning of 11th November the royalists had decide to re-supply their troops with match, powder and shot ready to march from Colnbrook toward London the next day.  A brigade of three royalist regiments at Windsor, which was to be involved in the assault on Brentford, had been similarly re-provisioned on 10th November.

In order to approach the capital, on the 12th November the royalists had to fight parliamentarian detachments at Brentford, to secure the crossing of a minor stream to enable the continued advance on London. Following the battle at Brentford, parliamentary artillery, match and powder were transported, according to one royalist account in fourteen barges, overnight down the river Thames from Kingston-upon-Thames toward London.  But these were spotted and engaged by royalist musketeers at Syon House near Brentford, though they appear to do little damage to the convoy.   However between the eastern end of Brentford and the modern day Kew bridge the royalists had deployed cannon covering the river and, judging they had no chance of escape, the parliamentarian sailors blew up the powder to scuttle the barges.  Separately on the afternoon of 13th November 1642, two parliamentarian vessels reportedly attacked Syon House with cannon from the Thames damaging the house. Royalist counter-fire is said to have sunk at least one of parliamentary vessels

On the 13th November 1642, the London Trained Bands were called out by the Earl of Essex and deployed with the parliamentary field army, then mustered at Chelsea fields, at Turnham Green. Three thousand parliamentary troops were also quartered at Kingston-upon-Thames and there was discussion amongst the parliamentarian command about ordering these forces to Hounslow in an attempt to encircle the King.  But Essex, despite having around 24,000 men at Turnham Green, appears to have been reluctant to risk the troops at Kingston as a separate force and instead ordered their redeployment to the City via the south bank of the Thames.

As the two armies faced each other John Hampden, a leading parliamentarian commander, pleaded with the Earl of Essex to strike. For a second time the 51 year old general had the opportunity to inflict a major defeat on the royalist forces, and for a second time he let a potentially war winning opportunity slip away. Was this, as many commentators suggest, simply the result of his innate lack of confidence? Or had he already begun to form the view, which would become all too apparent amongst parliament’s aristocratic commanders in the autumn of 1644, that destroying the king’s cause in a crushing defeat threatened the overthrow of the whole traditional order on which their own position rested?

With his army outnumbered two to one and a battlefield which constricted the use of his horse, the King ordered a retreat covered by dragoons at Brentford.  The royal army withdrew to Hounslow Heath and then went on to Kingston.  Following incursions into Surrey and the garrisoning of Reading the royal army retired into winter quarters in and around Oxford.

After Edgehill the king had squandered his only opportunity to strike at the capital and potentially to end the war at a stroke. Never again would the road to London lie open to a royalist field army, as it had in late October 1642. Never again would the king’s forces pose a credible threat to the city, which soon would be encompassed by the most extensive and complex fortifications of any garrison in England.

Whatever the real reasons, the failures at Edgehill and at Turnham Green had consigned the country to a long and bloody Civil War, a war that would only be finally decided when a new breed of commander took the stage.