Always worth airing caution MartinR with the accrediting foundation dates with actual structures, which is a common pitfall from the past. A foundation document does not necessarily relate to the buildings on the site. I include an inferred plan of the hospital chapel and accompanying text by Aymer Valence (a respective church authority of his time), both of which suggest the chapel, with its apsidal east end is of early twelfth-century and not late eleventh-century as a foundation document might imply.
Apart from the larger religious establishments (cathedrals and priories), it is thought that the early church builders following the Norman conquest preferred the square east end. A revival of the eastern apse, unless it was already in place prior to the Norman conquest, appears to have been favoured in the parish church from about c.1100 - 1125. Archbishop Lanfranc (first Norman archbishop) certainly didn't favour the apse in the parish church, all of which can be roughly dated to his term possess square east ends. The curving apse subsequently went out of fashion after c.1150 with numerous 'apses' being removed and squared off, these were subsequently extended in the following years.
