However this date is uncertain as his parents were not together in early 1545 and a letter of March 1566, from Mary Queen of Scots, indicates Darnley was then nineteen years old.
Međutim, taj je datum nesiguran, jer njegovi roditelji nisu bili zajedno početkom 1545., a u pismu iz ožujka 1566., škotska kraljica Marija I. govori da je Darnleyu tada bilo devetnaest godine.