The abbey church was laid out in 1095 and completed in 1115. In 1133 the abbey was burnt down, and documentary evidence from this time states that the cloister and other buildings were then relocated to the south of the church (CAR 1, 40-41. VCH 9, 303).<1><2> The church along with the rest of the abbey was demolished during the century following the Dissolution of the Monasteries by Henry VIII. Following the dissolution of the Abbey in 1539, the site passed to various individuals and was eventually acquired by the Lucas family who constructed a mansion and resided there until the mid 17th century. During the siege of Colchester in 1648, the former abbey was used as a royalist stronghold and sustained considerable damage in the fighting. With the exception of the extant, but restored gatehouse, the remaining abbey buildings seem to have been demolished in the 1660s. The abbey site was bought by the War Office in 1860 from the Baring family and stayed in military ownership until very recently (VCH 9).<2>

No plan of the monastery has survived, the nearest being what was shown on John Speed's map of Colchester published in 1611-12. This shows a number of buildings huddled together inside the abbey's defensive wall labelled 'St John's Abbey' and what appears to be the church's central tower still standing in isolation.

In 1988, CAT excavations during an extension to the east side of the clubhouse revealed a stone wall foundation believed to have been part of the abbey church (see Event ECC1566).<3>
An evaluation carried out by CAT in 2007 to the west of the Garrison Officers’ Club uncovered a few sections of monastic foundations, as well as Roman, medieval and post-medieval deposits buried beneath deep soil deposits (CAT Report 405). This was an important advance but the exposures were limited and inconclusive because the investigation was modest in scale.<4>
Nothing was seen of the abbey church itself until an archaeological evaluation undertaken by CAT in 2011 (CAT Report 601).<5>
The parts of the church exposed in the evaluation, undertakern between December 2010 and March 2011, were the west wall, the north and south nave walls, and internal walls which are probably the south wall of the north aisle and the north wall of the south aisle.
No superstructure survived. The only below-ground structure was a length of footings for the west church wall. The church had been completely demolished (probably in the 17th century), and all walls and floors removed.
Notable finds included painted glass and decorated floor tiles, presumably from the church structure.

The robbed-out remains of the southern-most foundation of the abbey church were uncovered in one of the foundation-pits for floodlights (for tennis courts) in February 2011 (CAT report 737).<6>

Note that MCC419 may also refer to the same heritage asset.