The girl presented after Rose is announced as "Lady Jane Radclyffe" who is being presented by "The Countess of Derwentwater". There hasn't been an "Earl of Derwentwater" since the title was forfeit in 1816 from the 3rd Earl.
His son, grandson, great-grandson and great-great grandson all used the title but were only "titular Earls". The 5th Earl married and his descendants used the title of Earl of Newburgh; this title belonged to the titular 5th Earl's wife and she held it in her own right.
It was inherited by her son - the titular "6th Earl of Derwentwater" - and there is no record of a "Lady Jane Radclyffe" in the records, nor an Earl of Derwentwater in 1922.
Since these characters should be added to the "List of Off-Screen Characters" what do we do?