With house prices and rents rising sharply, residential use of boats is turning out to be an attractive alternative to conveniently placed accommodation on land, especially in London. However, the use of moorings along the River Thames for residential use raises a number of planning issues, including whether the use of boats for residential (or any other purpose aside from incidental river purposes) needs planning permission at all and, if it does, what is the approach to the appropriate planning unit and intensification. The NPPF and PPG provide no guidance as to how to apply s.55 Town and Country Planning Act 1990 to these circumstances.
These issues fell to be considered by the High Court in R(KP JR Management Company Ltd) v London Borough of Richmond & Kew Marine Ltd  EWHC 84 (Admin.).
The Claimant challenged the Council's decision to issue a lawful development certificate to the Interested Party for the mooring of six residential houseboats at is mooring adjacent to Kew Bridge. The Claimant's principal complaints were that the Defendant Council erred in law by:
a) Failing to have regard to relevant considerations when determining the Interested Party's entire floating pontoon was a single planning unit, rather than the riverbed beneath each individual mooring.
b) Straying into an impermissible review of the planning merits of the impacts occasioned by intensified residential use.
c) Failing to have regard to the relevant policies of the development plan, which restricted new houseboat moorings, when resolving whether there were significant planning consequences from intensified residential use.
Lang J granted permission to bring judicial review but dismissed the Claimant's claim, holding that:
1) Following the Court of Appeal's decision in Thames Heliports Plc v London Borough of Tower Hamlets (1997) 74 P & CR 164, even where there is no physical connection between the boat and the riverbed, the use of the boat may amount to a material change of use from the ordinary and incidental use of the riverbed of the Thames, thus requiring planning permission (para.51).
2) The ordinary use of the Thames is "the activity of ships boats and other vessels passing over the water for the purposes of navigation, commerce trade and intercourse" per Ward LJ in Thames Heliports at pp.178-178.
3) "A decision-maker has to make a planning judgment as to the most appropriate planning unit, which is a matter of fact and degree. Where there is more than one relevant unit of occupation, the decision-maker has to make a judgment accordingly. The Court will not interfere with an exercise of planning judgment, and will only intervene if an error of law is established" (para.59).
4) The decision to treat the entirety of the Interested Party's mooring as a single planning unit was lawful and not vitiated by a failure to have regard to relevant considerations (para.65).
5) Whilst the advice within the officer's report, which Members accepted, did form qualitative judgments about the merits of increased residential use, the Defendant did not "confuse the task of assessing the on-site and off-site effects of the increased residential use to determine whether there had been a change in the character of the use with the different task of assessing the planning merits of any such effects ... there was inevitably an overlap between the two tasks when considering the evidence on the effects" (para.76).
6) A material change in use may arise by intensification of the number of houseboats at a particular mooring. However, the development plan policies which heavily restricted additional houseboat moorings and residential use generally on Metropolitan Open Land (which included the River Thames), were not relevant in deciding where there had been a material change of use because the development plan policies in question did not affect the character of the land and therefore did not give rise to significant planning consequences (para.78).
In addition to the above points, those promoting or resisting such schemes should carefully consider whether a given boat has become a "structure" and therefore requires planning permission in any event. The threshold for a "structure" is however high, as illustrated by the decision of the Court of Appeal in Tristmire Ltd v Mew  EWCA Civ. 912.
A copy of the judgment can be found here.
Dr Ashley Bowes appeared for the Claimant (instructed by Prospect Law Ltd).