The area lies north of the River Thames and extends from its historic and commercial core of Westminster and the West End to the Greater London boundary, much of which is formed by the River Colne. Some interpretations of the area include the boroughs of Brent and Harrow, making ancient Watling Street, the boundary in those outer areas. The constituent districts of West London were traditionally part of Middlesex.
The area emerged from Westminster, an area just west of the City of London, which owed its importance to the consecration of Westminster Abbey and after that, the establishment of the Palace of Westminster. Westminster and the West End are also part of Central London. The term West London is used to differentiate the area from other informal radial divisions of London, the Metropolitan Compass;North London, East London and South London.
The London Plan defines two areas of London as International Centres, the West End and Knightsbridge, both in the west of London. Five of the thirteen Metropolitan Centres in the Plan might be described as being in West London (dependent on definition of the area): Ealing, Hounslow, Harrow, Uxbridge and Shepherds Bush.
Eleven of the Plan's thirty-eight Opportunity Areas might be described as part of West London; Kensal Canalside, Paddington, Earl's Court and West Kensington, Harrow and Wealdstone, Park Royal, Old Oak Common, Southall, Tottenham Court Road, Victoria, Wembley and White City. One of the Plan's seven Intensification Areas, Holborn, could be described as part of the West.
The development of the area began with the establishment of the Abbey on a site then called Thorney Island, the choice of site may in part relate to the natural ford which is thought to have carried Watling Street over the Thames in the vicinity. Tradition dates the foundation to the 7th Century AD with written records dating back to the 960s or early 970s. The Island and surrounding area became known as Westminster in reference to the church.
The legendary origin is that in the early 7th century, a local fisherman named Edric, ferried a stranger in tattered foreign clothing over the Thames to Thorney Island. It was a miraculous appearance of St Peter, a fisherman himself, coming to the island to consecrate the newly built church, which would subsequently develop into Westminster Abbey. He rewarded Edric with a bountiful catch when he next dropped his nets. Edric was instructed to present the King and St. Mellitus, Bishop of London with a salmon and various proofs that the consecration had already occurred . Every year on June 29, St Peters day, the Worshipful Company of Fishmongers presents the Abbey with a salmon in memory of this event.
The Palace of Westminster subsequently developed, with Parliament being based there from its establishment in 1265. The presence of the centre of government as a distinct focus for growth, accompanied by the proximity of the City, ensured that western London was the fastest growing part of early London.
In 1720, John Strype's 'Survey of London' described Westminster as one of the then four distinct areas of London; in it he describes the City of London, Westminster (West London), Southwark (South London), and 'That Part beyond the Tower' (East London). The area now usually referred to as North London developed later.
As well as the proximity of the centre of government, the West End was long favoured by the rich elite as a place of residence because it was usually upwind of the smoke drifting from the crowded City. A further factor facilitating rapid growth in West London was the very large number of bridges linking the area to South London and the area beyond; by contrast, even today, there are no bridges east of Tower Bridge, partly as the river becomes wider as it heads east.
Like other areas of the capital, West London grew rapidly in the Victorian era as a result of railway-based commuting; with the building of the termini at Paddington and Marylebone, and the lines radiating from them, having a particularly profound effect. This trend continued in the twentieth century and was subsequently reinforced by motorcar-based commuting.
The size of London stabilised after the establishment of the Metropolitan Green Belt shortly after the Second World War.
The term 'West London' has been used for a variety of formal purposes with the boundaries defined according to the purposes of the designation.
The 2011 iteration of the London Plan included an altered 'West' sub-region, to be used for planning, engagement, resource allocation and progress reporting purposes. It consists of the London Boroughs of Brent, Harrow, Ealing, Hammersmith and Fulham, Hillingdon, Hounslow and the Richmond upon Thames. As well as including outer areas of West London, the sub-region also includes areas south of the river, not usually counted as part of West London; areas of the cross-river London Borough of Richmond upon Thames.
The 2004-2008 and 2008-2011 versions of the sub-region varied in their composition.
The W (Western) postcode area was introduced in 1857 to facilitate the distribution of mail. The postcode area is a sub-set of West London.