St James' Park was first opened in 1900 to accommodate St James' FC, a recent rebrand of Alnwick United Services who had won the North Northumberland League the season prior. Their first reference under this guise is 03/11/1900 in the Alnwick Guardian, when "The St James'" faced Percy Rovers - another Alnwick club.

The ground prior to this had been pasture a few hundred metres away from the local fever hospital and adjacent to the Alnwick & Coldstream Railway. A pavilion was added shortly after on the northern end but was primitive and appears to be just one room like a shed. At this time they played in the Northumberland League against teams like West Sleekburn, though friendlies were offered against fortress rivals Bamburgh and Morpeth Harriers. They went onto win the Northumberland Minor Cup in 1904.

Our first photographic glimpse is in 1949. The shed is still extant though a larger pavilion was constructed on the western end with two separate changing rooms and an open hut in the centre presumably for the dugout. This is certainly the same pavilion in situ today (or by 2014 at least, as per the excellent Groundhoppersdiary entry https://groundhoppersdiary.blogspot.com/2014/10/alnwick-town-st-james-park.html).

Alnwick continued to enjoy success in the middling echelons of the northern game, winning the Northern Alliance for the first time in 1937-38. They continued to win throughout the 60s and 70s, and eventually joined the Northern League Division Two in 1982. They earned promotion by the 88-89 season but were relegated a few years later. They sit in this league today at this same ground.