The M27 is a motorway in Hampshire, England. It is 27.9 miles (44.9 km) long and runs between Cadnam and Portsmouth. It was opened in stages between 1975 and 1983, providing the largest two urban areas in Hampshire with a direct motorway link. An extension into the county of West Sussex was planned but never constructed. A number of smaller motorways were proposed, connecting the city centres of Southampton and Portsmouth to the motorway; of these only the M271 and M275 were built. Three sections of the M27 have since been widened to four lanes each way, the first between junctions 7 and 8, the second between junctions 3 and 4, and the third begins at the slip road where junction 11 joins until mid-way to junction 12.

Southampton is a port city in Hampshire, England. It is located approximately 80 miles (130 km) south-west of London, 20 miles (32 km) west of Portsmouth, and 20 miles (32 km) south-east of Salisbury. Southampton had a population of 253,651 at the 2011 census, making it one of the most populous cities in southern England. Southampton forms part of the larger South Hampshire conurbation which includes the city of Portsmouth and the boroughs of Havant, Eastleigh, Fareham, and Gosport. A major port, and close to the New Forest, Southampton lies at the northernmost point of Southampton Water, at the confluence of the River Test and Itchen, with the River Hamble joining to the south. Southampton is classified as a Medium-Port City.