May Day (the day, not the call for help) used to be known as Beltane, which means ‘day of fire’. Beltane was an ancient Pagan festival. Bel was the Celtic God of the sun and marked the seasonal transition from winter to summer and celebrated the first spring planting.
(Nowadays, May Day is recognized throughout the world as International Workers’ Day, or Labour Day. In 1884 US and Canadian trade unions declared that after May 1st 1886, 8 hours would constitute a legal days work.
In previous centuries working people would take the day off to celebrate, often without the support of their employer.
William Davidson, a black trade unionist and a revolutionary, was executed on May Day 1820. Davidson was born in the then pirate capital, Kingston, Jamaica and put a skull and crossbones on a black flag to say:“Let us die like men and not be sold like slaves.” He was executed for being part of a conspiracy to kill the entire cabinet, which was hoped to give the spark to a revolution in Britain.
The USA and Canada do not recognize May Day. The US government attempted to erase the its history by declaring that May 1st was ‘Law Day’ instead. They pronounced that Labour Day was to be on the first Monday of September, a date of no particular significance.
You can read more about May Day in the UK here.)