The banns were required to be read in "the home" parishes of the bride and groom and additionally at the church where the ceremony was to be held if that was different from the home parishes. The banns usually were read up to 3 months before the proposed ceremony. I suggest to you that the banns should have been read in the Exeter church as well as Brushford and Coldridge and the later ceremony were probably by licence as the banns were usually for a period of 3 months. Does the marriage at Exeter show "by banns"?