Border Archaeology, on behalf of South East Water, undertook an Archaeological Observation (also referred to as 'Watching Brief') in respect of the western extent (Phase 1) of the Fleet PS to Greywell PS Mains Reinforcement Scheme. The programme of Archaeological Observation was carried out between 4th of April and 1st of August 2018. Phase 1 comprised a 2km section of a 13km route; the route extending from Greywell Pumping Station to a field located to the west of, and adjacent to Dunley's Hill Road (B3349). Off-road sections of the pipeline route comprised an initial topsoil strip, followed by traditional open-cut trenching to the required engineering depth for pipeline installation. The Archaeological Observation of the groundworks undertaken on the Fleet PS to Greywell PS Mains Reinforcement Scheme Phase 1 revealed only two features of archaeological significance, observed within two of the eight trenches making up the 2km section, Phase 1, of a 13km route. Both features were located in the area south-west of West Street; in the field adjoining Deptford Lane to the west and in the field south of the junction between Deptford Lane and Bidden Road. The most substantial feature of the two was rectilinear enclosure ditch [003004], uncovered within Trench 003. Although there is the potential that this may represent the extant remains of a medieval chapel noted in the Hampshire AHBR within this area, only further archaeological investigation, outside the scope of these works, will determine if there is any relationship between the rectilinear enclosure ditch and the Medieval chapel site.