Seton Church was dedicated in the names of St. Mary and the Holy Cross, and begun in the thirteenth century. In 1390, a south aisle was built by Catherine Sinclair, widow of William, the First Lord Seton. The Church was created a Collegiate Church on 20 June 1493. Additions were made by George, 4rd Lord Seton, and the 5th Lord Seton, and Lady Janet Seton (Hepburn) who generously endowed the Church. In 1544 it was damaged during the English invasion of the Earl of Hertford, and in 1580, the Church was united with Tranent and was well patronised until 1715 when it was entered by the Lothian Militia, incited that Lord Winton was a Jacobite, the Militia defaced the interior and demolished the tombs.