The monastery appears to have grown in importance during the Norman period, sitting roughly in the middle of the monastic income league for Dorset. More than Abbotsbury and Sherborne, but less than Shaftesbury and Cerne. Whilst not a lavish income, it was certainly enough to maintain a programme of building to replace the early temporary structures.
There was a catastrophic fire in 1309, caused by a lightening strike on the spire. Although the building of a replacement church was soon started, it took a long time and only reached its present size under Abbot William Middleton, who was elected in 1482. The delay was caused by a number of reasons. Arguably, the most important was the fact that the Abbey had become exceedingly lax with the brethren failing to adhere to the monastic rules to the extent that they were even keeping women! In addition, as has been mentioned elsewhere on this website, building in those days tended to be a slow process, partly because it depended on funds being available, but also partly due to the nature of the workforce. Construction only moved forward between March and September because the unskilled workers had to return to their land for the harvest in the autumn and could not leave until they had ploughed and sown their crops in the spring. Only the skilled masons etc. remained to work through the winter preparing stones for the next building season. So it needed a man of vision like Abbot Middleton to drive the project forward. Gradually a town, called Middleton, had developed alongside the Abbey and this had prospered, partly as a result of a weekly market and an annual three day fair, granted by a charter from King Henry III in 1252 and partly because it was on an important route between Blandford and Dorchester and was used by many pilgrims. By 1332, it was the biggest provider of a personal tax in Dorset demanded by the King to fund his wars with France