Eastern National RELH6G BN1604, BNO105B, with a dual-purpose 47 seat body. It was new in 1964 with fleet number 595 and renumbered in August that year to 1604. It was withdrawn in 1976.
I hope the driver had remembered to feed the money into the parking meters.

Photo from Essex Bus Enthusiasts Group collection, courtesy Chris Stewart, taken Southend Victoria Circus, London Road