River Westbourne

The Westbourne or Kilburn is a mainly re-diverted small River Thames tributary in London, primarily sourced from Whitestone Pond, Hampstead Heath and which, notwithstanding one main meander, flows southward through Kilburn and the Bayswater (west end of Paddington) to skirt underneath the east of Hyde Park's Serpentine lake then through central Chelsea under Sloane Square and it passes centrally under the south side of Royal Hospital Chelsea's Ranelagh Gardens before historically discharging into the Inner London Tideway. Since the latter 19th century its narrow basin has been further narrowed by corollary surface water drains and its main flow has been replaced with a combined sewer beneath its route.

The river was originally called the Kilburn (Cye Bourne – royal stream, '' being the Germanic word equivalent to rivulet as in the geographical term 'winterbourne') but has been known, at different times and in different places, as Kelebourne, Kilburn, Bayswater, Bayswater River, Bayswater Rivulet, Serpentine River, The Bourne, Westburn Brook, the Ranelagh River and the Ranelagh Sewer. It is of similar size to the Fleet.

Rising in Hampstead at Whitestone Pond the river flows south through Kilburn (also the name of the river at that point) running west along Kilburn Park Road and then south along Shirland Road. After crossing Bishops Bridge Road, the river continued more or less due south, between what is now Craven Terrace and what is now Gloucester Terrace. At this point, the river was known until the early 19th century as the Bayswater rivulet and from that it gave its name to the area now known as Bayswater. Originally Bayswater was the stretch of the stream where it crosses Bayswater Road, "Bayards Watering" in 1652 and "Bayards Watering Place" in 1654. It is said that there is a reference to Bayards Watering Place as early as 1380. There were a few houses at this spot in the eighteenth century and, it seems, a man called Bayard used or offered it as a watering place for horses on this road (formerly Uxbridge Road). The river enters Hyde Park at what is now the Serpentine and is within the park joined by a tributary, Tyburn Brook. The Serpentine was formed in 1730 by building a dam across the Westbourne at the instigation of Queen Caroline, wife of George II, to beautify the royal park. The Westbourne ceased to provide the water for the Serpentine in 1834, as the culverted Westbourne had become the most convenient main sewer and the Serpentine is now supplied from three boreholes from the upper chalk underneath Hyde Park. and was widely imitated in parks and gardens nationwide.

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