Astonishing as it may seem given the highly flammable nature of resin-rich Christmas trees, they were illuminated with candles. Great care was, of course, needed to stop the candle setting fire to the tree, particularly as the tree dried out over the festive season. It was for this reason that branches above the candle had to be carefully trimmed back. The candles were usually mounted on holders that had a dish of thin foil to catch any hot wax before it dripped and caused problems.
It is widely thought that the Protestant reformer Martin Luther was the first to add a lit candle to a Christmas tree in around 1525. The candle was lit on Christmas Day itself to symbolise Christ’s arrival as the ‘Light of the World’, a phrase used by Christ to describe himself in the Gospel of St Matthew.
Candles were expensive objects at the time, so the candle on a tree remained the preserve of wealthier German Protestants for many years. It was not until the mid-19th century that cheaper candles and greater wealth combined to make a candle on the tree a standard part of the festive season for middle class families. By the 1860s it was usual to have more than one candle, with some trees having a dozen or more lit on Christmas Day.
The first use of electric lights instead of candles came in 1882 as part of a marketing publicity stunt by the Edison Electric Light Company in New York. The cost of electric light bulbs meant that these fairy lights did not become popular until the 1930s when prices came down. In the 21st century LEDs have replaced light bulbs on Christmas trees.