What were Royal Navy ships required to provide by law when entering the Port of London?

The rum ration (also called "tot") was a daily amount of rum given to sailors on Royal Navy ships. It was abolished in 1970 after concerns that regular intakes of alcohol would lead to unsteady hands when working machinery.

The practice of compulsorily diluting rum in the proportion of half a pint to one quart of water (1:4) was first introduced in the 1740s by Admiral Edward Vernon (known as Old Grog, because of his habitual grogram cloak). The ration was also split into two servings, one between 10 am and noon and the other between 4 and 6 pm. In 1756 Navy regulations required adding small quantities of lemon or lime juice to the ration, to prevent scurvy. The rum itself was often procured from distillers in Jamaica, Trinidad & Tobago and the British Virgin Islands. Rations were cut in half in 1823 and again in half, to the traditional amount, in 1850.

Tot glasses were kept separate from any other glasses. They were washed on the outside, but never inside, in the belief that residue of past tots would stick to the side of the glass and make the tot even stronger. Sailors under 20 were not permitted a rum ration, and were marked on the ship's books as "UA" (Under Age).