Some years ago Port Strategy asked me to take up opinions from the European maritime industry about Brexit. The article was published in the special interest magazine. https://www.jannykok.nl/wp-content/uploads/2021/07/Port-Strategy-June-2021_PAGE-48-5.pdf Here is the article prior to subbing by the Editor:

David Cornwell, alias John le Carré, changed citizenship from British to Irish out of deep discontent about Brexit.  The European maritime trade and industry, in general, may be discontented as well because of Brexit.  It has been forced to comply with new rules and regulations since the UK left Europe. The Rotterdam organization of port and industry Deltalinqs and the European Sea Ports Organisation (ESPO) voiced the opinion of the majority when saying that being well prepared for Brexit is no guarantee for smooth trade between the EU and the UK. In short: uncertainty about the impact of Brexit and the related rules and legislations to be enforced still hampers smooth operations.

ESPO Secretary-General Isabelle Ryckbost hesitantly answers the question of whether British seaports and trade and industry were well prepared for Brexit.  The change is in adjusted documentation for the UK from that as a similar EU member state to a so-called Third Country. “As yet, not that much is clear and negotiations still going on. Recently we had a consultation with the European Commission about the subject. However, Brexit remains Brexit”, she says adding that this does not change the business relations between ESPO and British seaports. “A number of them are observer members with us. They remain our business friends. ”

This is not a guarantee that all is in the proper place. Since begin May 2021 the UK has implemented interim measures to keep trade going between Britain and the Continent. That may be respected as a kind of acknowledgement that still not everything is in place for Brexit.