Good call Matt. I should have remembered that ‘Livery’ and armorials apply to companies and trades too. The middle section of the motto does appear to be the ‘OF OVR’ part of their ‘at commandment of our superiors’ motto (for which there are multiple variations) and the ‘fish’ are heraldic dolphins.
A little history:
In Stow’s 1598 survey there were around 40,000 men earning a living on or about the Thames in London, including ‘watermen’ who carried passengers and ‘lightermen’ who carried goods and cargo. The Watermen’s Company was born in 1555 as a kind of regulatory body for their trade, as well as providing apprenticeships. The Lightermen joined the Company in 1700.
They still operate as a working guild today, participating in the traditions of the City of London and providing services to their ‘Freemen’… more than 390 boat owners and 500 ‘Journeymen’ who have completed a five year apprenticeship to become qualified Watermen/Lightermen (now called a ‘Boat Master’s Licence’).
The Livery Companies of the City of London represent historic trades such as the Fishmongers, Apothecaries and Vintners. Most members are generally known as ‘Worshipful Companies’ or ‘modern Livery companies’ if they obtained Livery after 1926. The Company of Watermen and Lightermen is recognised as a City company but is without livery for historic reasons and known simply as ‘The Company of Watermen and Lightermen of the River Thames’.
They still sell items carrying their armorial from their website (including souvenirs) but some of the items, such as buttons, are available only to Company Freemen… hence no pictures of those on the website shop. Here’s a car badge pictured from elsewhere.
