Princess_Marie_Louise_of_Bulgaria--Princess_Louise,_Duchess_of_Argyll

Princess Marie Louise of Bulgaria (Bulgarian: Княгиня Мария Луиза Българска; born 13 January 1933) also known as Marie Louise Borisova Saxe-Coburg-Gotha, is the daughter of Tsar Boris III and Tsaritsa Ioanna and the older sister of Simeon II of Bulgaria. Her baptism in the Bulgarian Orthodox Church caused controversy at the time because her mother had promised to raise her children as Catholics.
After the change in house laws into absolute primogeniture by her brother King Simeon II, Princess Marie Louise became the head of the house of House of Saxe-Coburg and Gotha-Koháry.