Near the Meon Marsh Sea Lock an information board assert confidentally that:
"According to the Parish Register, it was Henry, the Third Earl of Southampton, who completed the sealock in 1611 as part of an ambitious scheme to close the Meon estuary and replace the tidal channel with a canal. The mouth of the river was blocked and the salt marshes were reclaimed for pasture. This was a major enginering achievement and the canal is thought to be one of the earliest domestic navigation systems of its size and scale."
There are a number of problems with this, not least the fact that the Parish Register only states that, "Titchfield Haven was shutt out by one Richard Talbotts industrie under gods permisione at the costs of the right honorable the Earle of Southampton" on 24 June 1611. No mention of a canal.
Whether the waterway running from here to Titchfield was a navigable canal or just a feeder for an extensive system of water meadows, we will never know. All I would say is that for a sea lock, it is now and probably always was a long way inland.
The local authority web site details a round walk that incorporates the path alongside the canal. The latter is pleasant enough but I haven't done the return leg.
Henry Wriothesley, 3rd Earl of Southampton, who lived at nearby Titchfield Abbey, is probably best known as a patron and muse of William Shakespeare.