The early printing presses in Britain were imported from the continent where the letter thorn was not used, so they didn’t have a thorn letter. The printers use

The early printing presses in Britain were imported from the continent where the letter thorn was not used, so they didn’t have a thorn letter. The printers used either y or “th” (which was also already being used by scribes in place of thorn in parts of the country anyway) to replace thorn depending on how much space they had. Y followed by a superscript e was common way to print “the” when space was very limited.