The Midsummer Festival celebrates the summer solstice, which falls on June 21st in the Northern Hemisphere, though the festival itself is observed on different dates depending on cultural traditions. The original pagan festival was adopted by the early Church in Britain as the feast day of the Nativity of John the Baptist on 24th June, six months before the birth of Christ. In Scotland, Midsummer is known as the Eve of St John and in Wales it is Gwyl Ifan Ganol Haf (St John’s of Midsummer).
The summer can be a dangerous time of the year when food can quickly rot, and infections spread, due to the warm air. Customs therefore centred around purification rites, and bonfires were lit to protect the community from contamination and evil spirits. Such rituals were adopted by the Church, and before the Reformation the making of bonfires was central to the worship of St John the Baptist. In the fourteenth century John Mirk of Lilleshall Abbey in Shropshire gave an account of St John’s Eve:
Men stay up at night and make three kinds of fires: one is of clean bones and no wood and is called a “bonnefyre”; another is of clean wood and no bones, and is called a wakefyre, because men stay awake by it all night; and the third is made of both bones and wood and is called,
St. John's fire.
After the Reformation such practices were frowned on as, very often, the fire rituals were accompanied by drinking, singing and dancing. However, the rituals continued to be followed, particularly in rural areas, well into the nineteenth century.
In ancient times two small fires would be lit, between which livestock would be driven to protect them from disease, and people would leap over them to ward off evil. Obviously, this is a health and safety risk – so I would suggest making two fires which guests should walk (or dance) between.
In Scandinavia the burning of fires is accompanied by the decorating of houses with greenery and flowers. A Swedish neighbour once introduced us to the tradition of wearing garlands of flowers on the head at Midsummer parties. A bucket of flowers was provided, and each guest made their own garland using soft wire to bind round the stalks.