I came across this fascinating oddity at Turkdean in the Gloucestershire Cotswolds. When the parisioners decided to rebuild they modest two cell Norman church sometime in the fifteenth century. they decided to start by constructing the tower within the western bay of the Norman nave. They then built a new nave and chancel abutting the new tower. For some reason when the new nave, tower and chancel were completed the builders chose not to remove the remaining bits of Norman nave. So you have, in effect, two odd shallow Norman aisles, complete with half a door and corbel table, embracing the tower. Very strange.