Looking from the outside, the structure consists of a squat western tower, a nave with a 13th century south aisle, a chancel, and a south chapel built by Sir William Scott in the 15th century. The tower began to collapse in about 1700 so the upper stages were taken down and a huge buttress was constructed to strengthen the original 12th century stonework. There are many important features inside, the most special of which is the eastern most window on the north wall of the chancel. This is the only window in Britain that is complete with Norman glass in its original setting. This window is just as it was in the 12th century, the pattern of the leadwork corresponding in character with the string course beneath. In the chancel is what is almost certainly a heart shrine, built for the heart of John Baliol, founder of Balliol College, Oxford and father of John Baliol le Scot, King of Scotland. John Baliol died in 1269 and his widow had his heart preserved. She carried it with her in a casket of silver and ivory and it was buried with her in Scotland. Their son later brought the heart back to Brabourne after his defeat by Edward I. Eighteen generations of the Scott family, descended from Baliol, are buried in the church.