Lady Margarita Elizabeth Rose Alleyne Armstrong-Jones is the only daughter of an English furniture maker who is 18th in line of succession to what?  
Lady Margarita Armstrong-Jones: Lady Margarita Elizabeth Rose Alleyne Armstrong-Jones (born 14 May 2002) is the only daughter and youngest child of the Earl and Countess of Snowdon. David Armstrong-Jones, 2nd Earl of Snowdon:  The son of Princess Margaret, Countess of Snowdon, and of Antony Armstrong-Jones, 1st Earl of Snowdon, he is a grandson of King George VI and is 18th in line of succession to the British throne, the first in line who is not a descendant of Queen Elizabeth II.
i don't know