In June 1877, a boatman called Walford was fishing in the river Thames opposite Hampton Court, when he discovered a large block of wood on the river bottom. He decided to raise it to see what it was, as he knew the river at this spot very well and had never seen its like before. As Pitt Rivers later put it:
He had repeatedly sounded the river bottom in all directions, and nothing of the kind had attracted his observation up to that time; the block in question must, therefore, have been recently uncovered or must have been washed there from some part of the river higher up. On bringing it to the surface it was found to be part of a canoe of oak dug out of the solid tree, and in an advanced state of decay. Some parts of it were wanting, but sufficient remained to determine its size and function. [Pitt Rivers, 1878: 102]
Pitt Rivers heard about the canoe from Lord Arthur Russell  and went to see it some three weeks after it had been raised on 29 June 1877. He described it as:
It is flat-bottomed, the bottom rising slightly towards the front and stern, the bow is rounded, the sterm has evidently been square, but the back-piece is wanting; the sides are perpendicular, 15 inches in height, interior measurement, and the top has been level from end to end, not rising at the bow or stern; the greatest width, interior measurement, taken along the flat bottom, is 2 feet 6 inches, but this diminishes in front to 2 feet at the place where the scooped out bow commences. One side only is perfect from the bow for a distance of about two-thirds of its length, the whole of the starboard side is deficient except at the bottom; the sides and bottom are about 2 inches in thickness; the stern is strengthened along the bottom at 1 foot from the end by a raised ridge or "knee", 3 inches in width by 1 1/2 in height, carved out of the solid; whether this ridge ascended the sides or not cannot now be ascertained, as the sides are wanting in this part; towards the bow on the perfect side, at about 2 inches from the top, is a circular hole 2 inches in diameter, which may be used to fasten a stay, or may have served for the loop of a rowlock. The total length of the vessel from stem to stern is 14 feet, and the whole is carved out of one piece. The surface of the oak having been exposed to the sun for some time, was cracked and peeled so that it was impossible to discover any marks of the tool by which the interior had been excavated and it is feared that further damage may be caused by exposure. [Pitt Rivers, 1878: 102-3]
Pitt Rivers then reports on the river conditions at the find spot:
The original position of the canoe is not difficult to determine. The river between the bridge and the palace makes a re-entering bend on the south side just below the spot where the Mole runs in. Large quantities of the delta ground at the point were washed away last winter by an unusually strong flood, and there can be little doubt that the canoe which had originally grounded and become covered at the point, had then been washed down with the earth for a distance of about 100 yards into the place in which it was discovered. [Pitt Rivers, 1878: 103]
Along with the canoe, Walford (the boatman) told Pitt Rivers that he had spotted rows of piles at low tide, crossing the river near to where the canoe had been found. He had found many flint and stone celts in the area, from which Pitt Rivers concluded that 'in all probability, this place was much frequented during the stone age, or at any rate, the age in which stone implements continued in use, and proving, as in so many other instances of prehistoric discoveries in the Thames, that the river has changed its course but little, if at all, since that remote period'. [Pitt Rivers, 1878: 103]
Pitt Rivers read a short account to the June 1877 meeting of the Anthropological Institute, of which he was then Vice-President. This was published in the journal of the Institute in 1878.
The canoe is now in the Pitt Rivers Museum's collections.
Accession Book IV entry - 1884.54.1 - 59 Modes of Navigation Boats canoes rafts and accessories - Remains of an Ancient British canoe with horse's skull found on it Hampton Court 1877 10.8.77 (Ag 6955)
Black book entry - Ag 6955 10.8.77 Part of an ancient British canoe found in the Thames with part of a horse's skull 1351
Delivery Catalogue I entry - Remains of a British canoe with skull of animal on stand S 1351 Not in case 116
'Green book' entry - South Kensington Receipts, 13 August 1877 - of part of an ancient British canoe found in the Thames part of a horse's skull
[Geographical] Card Catalogue Entry - [English archaeology] Middlesex - England Middlesex Hampton Court 1351 Model of an ancient British canoe with horse's skull found in it 1877 Ag 6955 10.8.77 Original Pitt Rivers Collection
Hampton Court was then in Middlesex though it is now part of the London Borough of Richmond. It seems clear that this is the same canoe though it is strange that there was no mention in the report to the Anthropological Institute that there was a horse's head. It is clear that Pitt Rivers purchased or was given the remains of the canoe by Walford, and that he sent it to Bethnal Green Museum (where his collection was then displayed) on 10 August 1877. It was approximately the 7000th object to be sent by Pitt Rivers to Bethnal Green Museum (hence Ag 695). It was then listed in the delivery catalogue prior to transferring with the rest of the founding collection to Oxford. It is on display in the Court (Ground Floor) of the museum above Case 12.A. There is a discrepancy between all the other primary documentation sources and the geographical card entry which suggests that this is just a model. If that is correct then it was presumably made between June and August 1877.
Pitt Rivers/ Lane Fox A.H. 1878 ‘On the discovery of a dug-out canoe in the Thames at Hampton Court.’ Journal of the Anthropological Institute 7  102-3
 Lord Arthur John Edward Russell, MP, 1825-1892. Younger brother to the Duke of Bedford. Served as private secretary to the Liberal Prime Minister, Lord John Russell (his uncle).
An image of the place where the River Mole meets the River Thames at Hampton Court, and therefore where the canoe was found, is shown on the wikipedia entry for the River Mole.