Mile Oak is a locality forming the northern part of the former parish of Portslade in the north-west corner of the city of Brighton and Hove, England. Mile Oak is on the edge of the South Downs and as such has much farmland nearby; the Monarch's Way and Sussex Border Path long-distance footpaths skirt the edge of the built-up area. The first urban development occurred 1935 after the First World War, and the area grew substantially in the 1960s when Copperas Gap dockside dwellings were demolished. The inhabitants were rehoused to the area north of Portslade old village. Since the 1980s, Mile Oak has been intersected by the A27 dual carriageway, which has somewhat cut off the community from the rural surroundings.