The Ouzel rises in the Chiltern Hills, on the boundary of the two counties and for many miles thenceforth it forms the boundary of Bedfordshire and Buckinghamshire, initially as a small brook and growing to be a respectable river at Leighton Buzzard. North of that town, the Ouzel at last gives its allegiance to Buckinghamshire alone and flows through that county until it discharges its gathered waters into the Great Ouse at Newport Pagnell after a course of 20 miles.
The river is usually called the River Ouzel, except near Newport Pagnell where both "Ouzel" and "Lovat" are used. The name Lovat was recorded (in the form "Lovente") in the thirteenth century, and Herman Moll's map of 1724 marks the river as "Lowsel R". Thomas Jeffreys's map of 1765 shows it as "Ouzel River". The modern Ordnance Survey uses only the name Ouzel, except north of Willen Lake where it is marked as "River Ouzel or Lovat".
From springs just north of Dagnall, the Ouzel forms the boundary between Bedfordshire and Buckinghamshire. It is joined by the Ouzel Brook from Houghton Regis, and by Whistle Brook (also known at Ivinghoe as Whizzle Brook) from Pitstone. Near Grove Lock, just south of Leighton Buzzard.
The river was once joined by Ledburn Brook, which has since been diverted into the Grand Junction Canal (now the Grand Union Canal), which follows the course of the Ouzel from just south of Leighton Buzzard. At Leighton Buzzard, the river is joined by Clipstone Brook from Milton Bryan by way of Hockliffe and Clipstone.
To the north of the town the excess water from the canal is released into the river at the Twelve Arches. At Old Linslade, the Ouzel enters Buckinghamshire. The river then flows north to Milton Keynes and through that town, where it is joined by Water Eaton Brook. The Grand Union Canal parts company with the Ouzel at Milton Keynes and various loops of the two work north apart. As the Ouzel leaves the townscape it is joined by Crawley Brook from Husborne Crawley and very soon the river flows through Newport Pagnell to its junction with the Great Ouse.
- Eilert Ekwall, English River Names, Oxford University Press, 1928, p. 263.
- Herman Moll, Bedfordshire, reprinted in M. F. Hopkinson, Old County Maps of Bedfordshire, Luton Museum & Art Gallery, 1976, p. 21.
- Thomas Jefferys, The County of Bedford, reprinted by Bedfordshire Historical Record Society, 1983.
- Ordnance Survey, Explorer 192, edition A, 1998.
- F. G. Gurney, Yttingaford and the tenth-century bounds of Chalgrave and Linslade, Bedfordshire Historical Record Society 5, 1920, p. 175, note 25.