....seems like Salt Marsh too is mainly exported to France:
Salt Marsh Lamb
Salt Marsh Lamb offers a unique flavour due to them grazing over the natural grasses and samphire of the salt marshes in Romney Marsh in Kent. These marshes are free from any fertilizers and provide an environment where the sheep can roam freely.
The meat has a richer and altogether sweeter flavour. 90% of the UK's salt marsh lamb is exported to France where it is highly prized by their top chefs.