Starting from Loughton tube station (essex, easst north east london) go straight out the station and you can see epping forest up on the hill. Go straight up the road towards it. Follow this uphill road for about 2 miles till you reach high beach where there is an info centre, pub and tea hut. back track where you have come from about 100 metres till you see a small lake on the right, the trail you will see starts just past it.
Excellent trails for running.