The High Medieval period is generally defined as the period between the Norman Conquest (1066) and the ascension of Edward I (1272). The period pre and immediately post the conquest was covered in the Saxon and Normans page.

The most obvious feature is Thomas a’Becket church. The church was originally an abbey building possibly the guest house or infirmary. The oldest part of the church was built in about 1180. Originally an aisled hall with a small chapel at the east end it was converted to the parish church early in the 13th century.

The house is built on the foundations of a building of the Abbey. In the basement of the house is found the ‘Lady Chapel’. This is probably a misnomer. The remaining fabric makes up a room measuring approximately 20m by 7m, dating from the 13th Century, although there are features that indicate parts of the fabric are earlier. The room has an internal wall-arcade of moulded trefoiled arches with moulded labels and formerly resting on free shafts with moulded and foliated capitals and moulded bases. The arcading appears to have been continuous on the side walls except in the fourth bay from the East where on each side there is a doorway. There is a disparity in thickness of the walls suggesting that the structure was connected to others. There has been much discussion over the purpose of this room, possibly the Lady Chapel, a chapter house, infirmary chapel. It may just be that the function of the room changed use over time and shows characteristics of all.

As discussed on the Saxon and Normans page there was evidence of the abbey in the years immediately following the conquest.

The 1998 excavations identified another timber building from postholes and beamslots. This building remains had associated pottery dating it to mid-12th to mid-14th century. A much smaller building (2.5 by 3m) was ialso found. A recut ditch running east to west was seen, this ditch was over 4.6 metres wide and at least 1.8 metres deep. 6 metres north of the ditch was featureless suggesting that there existed a bank. This gives the impression of a defensive ditch, maybe dating to the Anarchy when Geoffrey de Mandeville occupied the Abbey. The ditch fill contained various plant remains including wheat, barley, peas as well as remains of other plants that indicate arable farming and the wet conditions. Other ditches were found defining paths or enclosures. Some pits were found, mostly containing rubbish and building material waste. One included a spread of limestone fragments, frequent charcoal and near complete peg tiles. Another nearby pit contained scorched clay, probably from a hearth or oven.

The RACP excavation of 2018 in Area 2 revealed more ditches. The largest, over 4m wide, and earliest ditch ran North-South. This ditch aligns with what is thought to be the Abbey precinct boundary, possibly a part of the Anarchy defences. There is a trackway running alongside the ditch which appears to be contemporary judging by the finds, this also suggests that there was a bank the other side so the ditch could have been part of the defences during the Anarchy.

Pottery from the 1998/2002 excavations is mostly Medieval Ely-type ware (c 1150–c 1350) , although a later review reclassified some as Huntingdonshire Fen Sandy Ware. This is confirmed by the classification of the pottery from the 2018 excavation.

Within the next phase determined by the OA East excavation of 1998 and 2002 a lode (water channel) was clearly visible. The main body shows in the 2002 target area with the end found in the 1998 target area. At points this channel was 8.7m wide and 1.45 m deep. The orientation matches that of the building described above, so is possibly contemporary in a smaller form but it would seem that the major work digging the channel was undertaken later. A jumble of features exist to the east of the lode. These include a flat based rectangular area, 1.7m by 1.2m which contains 3 postholes in a triangular arrangement. Along with the channel, the possible storehouse this suggests a crane for the loading and unloading of barges. The lode probably connected with Bury Brook/High Lode and thence to Ramsey Mere, Cnute’s Dyke and onwards to the network of waterways. However the route that this lode used is unknown.

As a side note 13th century pottery was found in 1978 and then later during the construction of new houses to the east of Wood Lane to the north of the abbey. The archives from the time indicate that this location was being used as a rubbish dump.