A 2009 Early Day Motion in the House of Commons by canoeing enthusiast John Grogan MP stated :
Some rivers, or non-tidal parts of rivers, such as the Thames in England and the Spey in Scotland, have been subject to public rights of navigation since time immemorial. In the case of the latter a clash between canoeists and the owners of valuable fishing rights reached the House of Lords, where Lords Wilberforce and Hailsham considered with some relish cases on the right to float logs downstream, from Quebec (based on its pre-revolutionary French civil code) and New York State (based on English common law). Lord Hailsham observing that “what I have now held to be the law of Scotland happens to coincide with what I believe to be the law of England”, the House determined :
- that a public right of navigation in a non-tidal river depends not only upon the theoretical navigability of the river, but also on proof of its regular, habitual use as a channel of communication or transportation from time immemorial (customarily 40 years);
- that a right of navigation is not a servitude and cannot be lost by non-use;
- that use for mere recreation is as effective to prove navigability as use for transporting goods or other commercial use;
- that no question arises as to whether the use is of sufficient public benefit;
- that the establishment of a right of navigation in a river is not subject to the same requirements as the constitution of a right of way on land, and in particular that a right of navigation need not be established between two public places;
- that the public right of navigation in the River Spey would permit navigation by any vessel that could be reasonably described as a boat, including a canoe.
The Court of Appeal has more recently confirmed that, where common law navigation rights over the Thames had been extended by statutory ones but their exercise over a particular stretch of water had long fallen into disuse, the Act did not restrict public rights of navigation which existed before its coming into force and could not confer any new right on a riparian owner to exclude any person from exercising such rights. However, where the actions of the navigation authority had led purchasers of a riverside estate to believe the waters were private these were sufficient to give rise to a legitimate expectation (albeit more limited in scope than the right to continue to enjoy the stretch of river as private which they contended for), and such an expectation relating to property could be a “possession”, the peaceful enjoyment of which was entitled to protection underarticle 1 of the First Protocol to the ECHR unless the interference by the authority with that possession was justified and proportionate.
Once acquired, a public right of navigation is not easily lost; and not by mere disuse. However, it can be lost through natural causes, such as an accumulation of mud rendering navigation impossible. If a river is obstructed in such manner this does not however give the public the right to cut another passage through adjoining lands, and when a navigable river has been obstructed for a long time and there is nothing to show how the obstruction came to be there, it may be presumed that the public right of navigation has ceased and the obstruction may not be removed. However, the right is not lost if the river changes its course since it will be exercisable over the new channel.
 Port of London Authority v Ashmore  EWHC 954 (Ch); now [2010 EWCA Civ 30;  4 All ER 665
 EDM 1577, 2nd June 2009
 Williams v Wilcox (1838) 8 Ad & E 314; but see Moore v British Waterways Board  EWCA Civ 73;  Ch. 488
 A-G (ex rel Yorkshire Derwent Trust Ltd) v Brotherton  1 AC 425,  1 All ER 230
 Wills Trustees v Cairngorm Canoeing & Sailing School Ltd 1976 SC (HL) 30
 In Scotland only
 (1972) 225 Estates Gazette 89
 Vol 101 (2009), para 703, fn 8
 Rowland v Environment Agency  EWCA Civ 1885;  Ch. 1
 Thames Preservation Act 1885
 R v Montague (1825) 4 B & C 598 at 604–605 per Holroyd J
 Carlisle Corpn v Graham (1869) LR 4 Exch 361