The Library's print was undated, so how can we tell when it was photographed? There are two telling details, datable through contemporary editions of Our Town:
The Methodist Church at Price and N. Essex is a construction site.
Our Town reported June 14, 1929 "the ground breaking for the new Methodist Episcopal Church at Essex and Price Avenues, Narberth, last Sunday [June 9]…. Actual work on the operation commenced Tuesday morning [June 11]. The contractor hopes to complete the work by April, 1930."
The exterior of the 300 N. Essex apartments ("Narberth Hall" in 2017) appears substantially complete.
Our Town, May 24, 1929: "Narberth's largest apartment house is now in course of construction on the property at 300 Essex Avenue…. It is expected that these apartments will be available for fall occupancy."
The full foliage with no hint of color change guides us settle on the summer of 1929.
The Dallin Aerial Survey Company produced aerial photographs between 1924 and 1941. You can see over 8,000 of them at The Hagley Museum Digital Archives. Subsequent research in this collection turned up this image as file ID# 70.200.05124 dated 1929 August 26.
See another Dallin aerial photo of Narberth at Northside aerial, 1939.