The Upper Tribunal (Tax and Chancery Chamber) has heard an appeal against a decision that the owner of a houseboat moored on a tidal section of the River Thames had acquired adverse possession of an area of the river bed beneath his boat.

The Port of London Authority (PLA) had applied to HM Land Registry for first registration of its title to part of the bed and foreshore of the River Thames between Key Bridge and Brentford Ait. A number of objections were raised. All were determined by the First Tier Tribunal ('FTT'), apart from that of Mr Mendoza.

Mr Mendoza lived on a houseboat, the Wight Queen, moored on the north bank of the Thames, an area where the river is tidal. Twice a day at low tide the boat rests on the river bed.

Mr Mendoza accepted that the PLA had paper title to the land in question but he claimed to have acquired title by adverse possession of the area of the river bed where the boat was moored.

In order to succeed in his claim Mr Mendoza needed to establish that there had been adverse possession of the riverbed beneath his boat for a period of 12 years before the date on which the PLA applied for first registration of the land. To do this he had to fulfil two criteria: that he was in factual possession of the land during this time; and that he had the requisite intention to possess that land.

The FTT found in favour of Mr Mendoza in relation to that part of the area occupied by his boat but the PLA appealed on the basis that the FTT judge had erred in finding that Mr Mendoza had the requisite intention to possess the land.

Permission to appeal was granted to decide the important question of whether the 'mere' act of mooring a vessel is, in itself, an act of such an equivocal nature that it is sufficient to establish the necessary intention to possess.

In Port of London Authority v Paul Mendoza [2017] UKUT 146 (TCC), Judge Elizabeth Cooke explained that, to establish his claim, Mr Mendoza had to show that he (and his predecessor) had the requisite intention to possess the land during the requisite time period and that it was apparent to the world at large that Mr Mendoza (and his predecessor) was in possession of the riverbed and was there to stay, with the intention of keeping everyone else off that land.

The PLA argued that Mr Mendoza's boat could have been moored for a number of reasons including with the permission of the London Borough of Hounslow or in the exercise of a public right of navigation, which includes a right to moor for short periods. The act of mooring in itself does not give anyone an insight into a boat owner's intentions. As Mr Stoner QC, for the PLA said 'it cannot be that, without more, every person who moves their vessel up and down the River Thames is to be taken to have the intention to possess the land under and around the vessel.'

The Judge agreed. She found that Mr Mendoza's possession of the land was ambiguous because it was open to several interpretations. Whatever discussions he had had with neighbouring boat owners, he did not make his intentions manifest to the world, including to the PLA.

The Judge concluded that there is no authority to the effect that simply mooring a boat is, without more, both factual possession and sufficient evidence of an intention to possess such that a finding of adverse possession can be made.

Courts will need to review the facts in each case in order to determine whether adverse possession of a river bed can be made out.