The A3, known as the Portsmouth Road or London Road in sections, is a major road connecting the City of London and Portsmouth passing close to Kingston upon Thames, Guildford, Haslemere and Petersfield. For much of its 67-mile (108 km) length, it is classified as a trunk road and therefore managed by National Highways. Almost all of the road has been built to dual carriageway standards or wider. Apart from bypass sections in London, the road travels in a southwest direction and, after Liss, south-southwest.

Guildford is a town in west Surrey, England, around 27 mi (43 km) south-west of central London. As of the 2011 census, the town has a population of about 77,000 and is the seat of the wider Borough of Guildford, which had around 145,673 inhabitants in mid-2022 est. The name "Guildford" is thought to derive from a crossing of the River Wey, a tributary of the River Thames that flows through the town centre.