Question: The River Bourne is the name given to a Thames tributary in northwest Surrey, England which has a longer tributary, the Windle Brook, that rises nears Bagshot Park, a royal residence located near Bagshot, a village 11 mi south of Windsor and approximately 11 mi north west of Guildford, owned by who?

Context paragraphs:
Windlesham: Windlesham is a village in the Surrey Heath borough of Surrey, England and civil parish that covers Bagshot and Lightwater in the same borough.  Its name derives from the Windle Brook which runs south of the village into Chobham and the common suffix 'ham', the Old English word for 'homestead'.

Wallingford, Oxfordshire: Wallingford is an ancient market town and civil parish in the upper Thames Valley in England.  Historically in Berkshire, it was transferred to Oxfordshire for the purposes of administration in 1974.  Wallingford is situated 12 mi north of Reading, 13 mi south of Oxford and 11 mi north west of Henley-on-Thames.  The town's royal but mostly ruined Wallingford Castle held high status in the early medieval period as a regular royal residence until the Black Death hit the town badly in 1349.  Empress Matilda retreated here for the final time from Oxford Castle in 1141.  The castle declined subsequently, much stone being removed to renovate Windsor Castle.  Nonetheless the town's Priory produced two of the greatest minds of the age, the mathematician Richard of Wallingford and the chronicler John of Wallingford.

Bagshot Park: Bagshot Park is a royal residence located near Bagshot, a village 11 mi south of Windsor and approximately 11 mi north west of Guildford (Grid reference: [ SU 9164] ).  Owned by the Crown Estate it is the current home of Prince Edward, Earl of Wessex and the Countess of Wessex.  Bagshot Park is on Bagshot Heath, a fifty square-mile tract of formerly open land in Surrey and Berkshire.  Bagshot Park occupies 21 hectares within the designated area of Windsor Great Park.  It is only a few miles from Sunninghill Park, the former residence of the Duke and Duchess of York.

Bagshot: Bagshot is a small village in the southeast of England.  It is situated in the northwest corner of Surrey within the county's Surrey Heath council district, close to the border with Berkshire, and is also in the diocese of Guildford.  In the past, Bagshot served as an important staging post between London, Southampton and the West Country.  Evidence of this can be seen in some of the original coaching inns that are still there today.

River Wey: The River Wey is a tributary of the River Thames in south east England and one of two major tributaries in Surrey.  It begins as two branches rising outside the county which join at Tilford between Guildford and Farnham.  Once combined the flow is eastwards then northwards via Godalming and Guildford to meet the Thames while in Surrey.  The main sub-tributary is the Tilling Bourne flowing from the western slopes of Leith Hill in Surrey westwards to a point just south of Guildford between the main village of Shalford and its Peasmarsh locality.  Downstream the river forms the backdrop to Newark Priory and Brooklands.

Longest rivers of the United Kingdom: There seems to be little consensus as to the lengths of rivers in published sources, nor much agreement as to what constitutes a river.  Thus the River Ure / River Ouse can be counted as one river system or two rivers.  If it is counted as one, the River Aire / Yorkshire Ouse / Humber system would come fourth in the list, with a combined length of 161 mi and indeed, the River Trent / Humber system would top the list with their combined length of 222 mi (357 km).  Also, the Thames tributary, the River Churn, sourced at "Seven Springs" adds 14 miles to the length of the Thames (from its traditional source at Thames head).  The Churn/Thames' length at 229 mi (369 km) is therefore greater than the Severn’s length - 220 mi (354 km).  Thus, the combined "Churn/Thames" river would top the list.  Sue Owen et al. in their book on Rivers generally restrict the length to the parts that bear the correct name.  Thus the River Nene is quoted at 100 mi , but would be around 5 mi more if the variously named sources were included.  Many of the above lengths are considerably different from Sue Owen's list, some longer and some shorter.

Chorley: Chorley is a market town in Lancashire, England, 8.1 mi north of Wigan, 10.8 mi south west of Blackburn, 11 mi north west of Bolton, 12 mi south of Preston and 19.5 mi north west of Manchester.  The town's wealth came principally from the cotton industry.

River Bourne, Addlestone: The River Bourne is the name given to a Thames tributary in northwest Surrey, England which has a longer tributary, the Windle Brook, that rises nears Bagshot Park in the south of Swinley Forest, Berkshire, merging with it while flowing through villages north of Woking; downstream the Bourne joins the Thames near Weybridge.

Chertsey: Chertsey is a town in the Runnymede borough of Surrey, England on the right bank of the River Thames where it is met by a corollary, the Abbey River and a tributary, the River Bourne or Chertsey Bourne.  It is within a narrow projection of the Greater London Urban Area, aside from the Thames bordered by Thorpe Park, junction 11 of the M25 London orbital motorway, the town of Addlestone and south-western semi-rural villages that were formerly within Chertsey (Lyne, Longcross and Ottershaw).  Chertsey is centred 29 km southwest of central London, has a branch line railway station and less than 1 mi north of its developed centre is the M3 (motorway).

Bisley, Surrey: Bisley is a village and civil parish in the borough of Surrey Heath in Surrey, England.  It is centred 3.4 mi west of Woking.  Of medieval creation, Bisley neighbours 19th century West End, centred 900 metres north, across the Windle Brook.  According to the 2011 Census, the population was 3,965, which is largely within a focal area with the surrounding green and heather-and-gorse heath buffer land lightly populated, in contrast to Knaphill which is contiguous to Woking, 1 mi east and is suburban to Woking.

Supporting paragraphs: River Bourne, Addlestone Bagshot Park
Answer: Crown Estate