An archaeological watching brief was maintained in May 2007 on a contractor's excavation of a thrust-bore pit in Flagstaff Road, immediately west of the north end of Abbey House, Flagstaff Road, Colchester Garrison, Colchester. The centre of the thrust-bore pit lay 7.5m west of the projected line of the west face of the western precinct wall of St John’s Abbey. <1>

Exposed archaeological remains consisted of the remains of an in situ wall foundation (F1 and F4) located on the eastern edge of the circular contractor's trench. The top of this foundation was only 0.25m below modern ground-level, ie the surface of Flagstaff Road. It consisted of ragstone, mortar and septaria randomly spread throughout a very light yellow sandy mortar matrix; there was no visible coursing. Its maximum surviving width and depth were 0.42m and 0.24m respectively. The combined maximum length of F1 and F4 was 2.2m north to south.
The wall foundation lay parallel to the abbey precinct wall, and was presumably a part of a substantial undated structure of some kind. Either a medieval or post medieval date is possible, and it may be the remains of the foundation of a post-Dissolution building erected against the outer face of the abbey precinct wall.
A large, undated post-hole 0.32m wide and 0.47m deep (F3) was found on the immediate west side of the wall foundation. The two may be associated.
The wall foundation was cut by a large pit F2. The exposed part of this pit measured 1.9m x 0.25m, but the curvature of its sides indicated that it was clearly larger than this and lay mainly off-site. It was dated by Victorian glass. Most of the north-west sector of the contractor's trench was occupied by post-medieval pit F5, which was dated by peg-tile. This measured 2.3m x 1.3m on-site, but most of it probably lay beyond the site edge.