Mark Francis Napier was the fourth and youngest son of Francis and Nina Napier. Francis, also known as Lord Napier, served as the British Minister to the United States from 1857-1859. During this time the Napier family lived in Washington DC and were close with the Seward family. Fanny Seward recounts taking dancing lessons with Mark and his brothers in her 1858-1859 diary, and also seeing them during social visits. 

Mark grew up to have a political career and was a member of the Scottish Liberal Party. He served as the Member of Parliament for Roxburghshire from 1892-1895.