Althorp Papers. Vols. mdx, mdxi. Letters from Spencer's cousin, William Alleyne Cecil, firstly as Lord Burghley, then from 1867 as 3rd Marquess of Exeter. Also included are copies of occasional replies by Spencer; 1857-1889. Two volumes.
Althorp Papers. Vols. mdi-mdiv. Letters from his half brother, Charles Robert Spencer, (Bobbie), later 6th Earl Spencer. For Spencer's letters to him, see R1-R9; 1866-1910. Four volumes.
Althorp Papers. Vol. mdix. Letters from: 1. His aunt, Isabella, Marchionness of Exeter; 1851-1874. 2. Brownlow Cecil, 2nd Marquess of Exeter and husband of Lady Isabella. Includes a copy of a reply from Spencer; 1851, 1860-1866.
Althorp Papers. Vol. mdxix. 1. Letters from Charles George, 5th Baron Lyttelton and 8th Viscount Cobham. Includes copies of occasional replies by Lord Spencer; [circa 1863], [1875?]-1889. 2. Letters from Neville Gerald Lyttelton, brother of Charles George, 5th Baron Lyttelton; [circa 1874]-1908.
Althorp Papers. Vol. mdxxv. 1. Letters from Lily Seymour, wife of Horace Seymour; many undated, but circa 1900-1909. 2. Letters from Freda Biddulph, Charlotte Spencer's niece; 1903-1910.
Althorp Papers. Vol. mdxiii. Letters from: — 1. His aunt, Lady Sarah Lyttelton, wife of William Henry, 3rd Baron Lyttelton and daughter of George John, 2nd Earl Spencer; 1851-1868. 2. His cousin, Caroline Lavinia Lyttelton; 1851-1881.
Althorp Papers. Vol. md. Letters from his sister, Lady Sarah Spencer. For Spencer's letters to Sarah see Add. MSS 77720-77722 below; 1851, [1856?]-1910.
Althorp Papers. Vol. mdviii. Letters from: 1. His uncle, George Spencer, known as Father Ignatius, Superior of the Order of Passionists in London; 1858-1863. 2. His aunt Frances, Dowager Lady Clinton; 1851-1872, n.d.