From a set of four stamps issued in 1979 to commemorate the 150th anniversary of the Metropolitan Police. This PHQ stamp card shows the River Police Thames patrol launch in what must be the Thames estuary because there is no land in sight. It was the designer, Brian Sanders', first set for the Royal Mail.
Another set he designed, in 1981, is equally good for this week's theme, features the fishing industry.
This, again one of four, shows cockle dredging. Cockles are small edible shellfish. There are many different species but most live in sandy beaches between low and high tide levels.
This is a post for Sunday Stamps, now hosted by Violet Sky at "See it on a Postcard!"