MSS.7201-7375 is a large group of original letters sent to George Combe. They show the trends which Combe's career took. The first few years are occupied with chiefly family and legal matters, including frequent correspondence from his brother, Dr Andrew Combe, who was also a fervent worker in the cause of phrenology. From 1820, the letters are from figures prominent in the struggle either to reject or to accept its truth. After 1845, writers include men outstanding in the field of education, both in America and Britain, seeking Combe’s views and advice.

MSS.7376-7398 are drafts and copies of letters written by Combe, now arranged in three divisions: drafts of letters, letter-books, and letter copy books, which were used when Combe was absent from home.

The letter-books contain a large proportion, but by no means all, of his replies to the letters in the first section (MSS.7201-7375).