The British honor their mothers on the fourth Sunday of May. The first was celebrated sometime in the 1600s on “Mothering Sunday” which has since become known simply as Mother’s Day. It’s usually celebrated with a family lunch where moms are presented with a rich almond cake (often called a “Mothering Cake” or a “Simnel Cake”).
Historically, during the early 17th century, Christian people in the U.K. returned to the main church or cathedral of the area (also known as the “mother church”) for a service to be held on Laetare Sunday (the fourth Sunday of Lent, usually falling between March 1st and April 4th).
In later times, Mothering Sunday became a day when domestic servants were given a day off to visit their mother church, usually with their own mothers and other family members. It was often the only time that whole families could gather together, since on other days they were prevented by conflicting working hours, and servants were not given free days on other occasions. The children would pick wild flowers along the way to place in the church or give to their mothers. Eventually, the religious tradition evolved into the Mothering Sunday secular tradition of giving gifts to mothers.
Later on, when Mother’s Day holidays celebrations gained prominence across the rest of world (the day was celebrated in May), merchants saw the commercial opportunities in the holiday and began relentless promoting it in the U.K. and after a while the newly imported tradition merged with those of the wider Catholic and secular societies.
Soon Mother's Day and Mothering Sunday became mixed up, and many people think that they are the same thing. As such the U.K. celebrates its Mother’s Day on the fourth Sunday of May.