It was in the year 1756 that the painstaking historian, William Maitland, F.R.S., announced that he had been so fortunate as to light upon the course of the long-lost trench of King Cnut.
He had found certain evidence, he said, of its course, in a direction nearly east and west from the then 'New Dock' of Rotherhithe to the river at the end of Chelsea Reach, through Vauxhall Gardens. The proofs were, first, certain depressions in the ground; next, the discovery of oaken planks and piles driven into the ground for what he thought was the northern fence of the canal, near the Old Kent Road; and next a report that, in 1694, when the wet dock of Rotherhithe was constructed, a quantity of hazel, willow, and other branches were found pointing northward, with stakes to keep them in position, forming a kind of water fence, such as, it is said, is still in use in Denmark. It will be seen that Mr. Maitland's theory has but a small basis of evidence, yet it seems to have been generally accepted--partly, I suppose, because it was so colossal.
The canal thus cut would actually be a little over four miles and a half in length. Another writer, seeing the difficulties of so great a work, suggests another course. He would start from the site of the New Dock, Rotherhithe, and end on the other side of London Bridge, a course of only three and three-quarter miles!
Let us ask ourselves why it should be a 'deep' ditch; why it should be a long ditch; why it should be a broad ditch.
Wherever Cnut began his trench, whether at Rotherhithe or nearer the Bridge, he would have the same preliminary difficulties to encounter: that is to say, he would have to cut through the Embankment of the river at either end, and he would have to cut through the Causeway in the middle. In these cuttings he would perhaps have to take down two or three houses, huts, or cabins, all deserted, because the people had all run across the Bridge for safety at the first sight of the Danes, if there were any people at the time living in Southwark--which I doubt.
We may, further, take it for granted that Cnut had officers of sense and experience on whom he could depend for carrying out his canal in a workmanlike manner. A people who could build such perfect ships would certainly not waste time and labour in constructing a trench which would be any longer or deeper or wider than was absolutely necessary.