The avenue leading from Main Road, New Town, to the Orphan School buildings was an integral part of John Lee Archer's original design. Although Blackburn's watch houses were not built until 1841, Charles Bruce's etching in 1831 depicts two watch houses in a similar location. While there is no evidence that they were built, the avenue itself was an original strong design feature.
Blackburn's watch houses still stand at the entrance to St John's Avenue. The black oaks which line the avenue were planted to commemorate Queen Victoria's Diamond Jubilee in 1897. In the 1920s, the Church of England red-brick rectory was constructed at the end of the avenue, near St John's Church. A smaller weatherboard building, now used as St John's Parish Centre, was constructed opposite at a much later date.