In 1990 Thamesway - the London tendered operations unit of Eastern National, operating from Walthamstow and Ponders End - won the contract to operate route 307: Brimsdown Station - Ponders End - Enfield Town - Barnet (Arkley Hotel). For this the company bought four new Leyland Olympians with Leyland bodies, numbered 1001-1004. They were painted in the new company livery of yellow and maroon.
Elderly Bristol VRs, in Eastern National Citybus green and yellow provided support. These were phased out, and middle-aged Leyland Olympians with ECW bodies were drafted in to replace them. These were numbered 4000 upwards. These also found employment on the old Westcliff-on-Sea service 251 between Southend and Walthamstow, and on the associated 551 and 351 routes.
The 307 contract went to Leaside Buses in late 1995, to be operated by Darts, and the still-young 1001-4 went on to Eastern Counties with First. In March 1996 Thamesway was reorganised into Essex Buses, and the remaining double-deckers were transferred away within the new organisation.