Jackdaw33 The seaweed was NOT a storage medium. It was and still is used as a natural and free free fertilizer, it just washed up on the beaches was collected and put on the spuds.
http://www.jerseyroyals.co.uk/about-jersey-royals.aspx
It is still used by a few traditional Jersey farmers but Jersey Royals are such a huge business now that there is nowhere near enough seaweed to use, so the huge majority (over 95%) are fertilized with ordinary commercial fertilizer.
The EU has NOTHING to do with it . In fact the EU has registered 'Jersey Royal' as a name for a type of potatoes grown in Jersey. Like 'Champagne' is a registered name for a type of sparkling wine from a particular region of France. The use of seaweed as fertilizer for Jersey Royal potatoes has also been endorsed by the EU.
So your contention that the lack of taste to Jersey Royals is due to EU regulation is the exact opposite of the truth. The EU have in fact endorsed the method of farming them and registered the name so that no other potatoes can be sold as 'Jersey Royal'