It was 18 months ago that ships around the world gave an audio "thank you" to seafarers on behalf of the public with the sound of ship horns.

"Our seafarers are the unsung heroes of global trade and we must not forget the contribution they are making," the International Chamber of Shipping said.

The symbolic — and appropriate — gesture followed on from the example of the public coming out of their homes mid-lockdown to clap for nurses and doctors.