Eastern National CN3500, WNO546L, Bristol VR / ECW O39/31F, new in December 1972 as 3026 and converted to open top in June 1986. Entered service on Clacton Coastliner routes in this red and yellow livery, but, due to competition from Coastal Red, the red areas were repainted green in May 1987, one month after this photo was taken.
Shown on an unusual working in Colchester in bright April sunshine. The Leyland National on the left (see higher resolution picture) is 1872, ANO 271S, one of only two LNs delivered with ANO registrations.

Photo taken by Eric Thompson, April 1987, Colchester Bus Station