If there’s a Great St. Mary’s (GSM), then one can surmise that perhaps there is a Lesser version. In this case, Little St. Mary’s (LSM) is the match to St. Mary’s Great Church. Little St. Mary’s is older than GSM — but how much older is not really known. The LSM website says:
There has been a place of worship on the current site, originally outside the town boundary, since at least the early twelfth century. According to the earliest known records, the first church here, called St Peter-without-Trumpington Gate, was controlled by three successive generations of the same family until 1207. Then it was given to the Hospital of St John the Evangelist, now St John’s College, and served by chaplains from that foundation.
Like mentioned, once known as St. Peter’s-without-Trumpington-Gate, elements of the name exist in the area surrounding the church. It’s on Trumpington Street next to Peterhouse. Not sure how the gate fits in, but the Peterhouse story is interesting.
In the 1280s the Bishop of Ely lodged some scholars in the hospital but quickly discovered that the students and sick people did not get on very well together. He moved the students to a more congenial site in 1284, two houses south of St Peter’s, allowing them the use of the church as their chapel. This was the origin of Peterhouse, the first Cambridge College.
Beyond all of this, most guide books are pretty quick to also point out that Godfrey Washington, the great uncle of George Washington, was a vicar at Little St. Mary’s.