Consequences of the battle of Edgehill
Although Edgehill is often viewed as an indecisive battle, in effect a bloody draw, the king had actually gained an important advantage. Essex had failed to break through and had retreat northward, to the security of the parliamentarian garrison at Warwick. He subsequently retreated back to London via Northampton, Woburn and St Albans arriving in the capital on 7th November. But in the meantime the royalists were left in command of the road to London, and control of the capital was the key to the war.
But matching the over cautious approach of his opponent, the king ignored the advice of Prince Rupert to immediately strike out for the capital. Instead he frittered away vital time. First he captured the nearby town of Banbury(27th October) and, moving south, on the 29th October he entered the city of Oxford, which was garrisoned and would become the royalist capital for the rest of the war. Next he took Reading (4th November) and only then did he march on London.
Those few crucial days allowed Essex to regain the initiative. By the time the royalists finally approached London the Earl had been able to bring his army back to the capital and to muster the 6,000-8,000 strong London Trained Bands in support. The major roads approaching London from the west and north west had all been secured by parliamentarian forces.