Douglas James William Kinnaird (1788-1830) and Lord Byron were close friends and wrote to each other regularly. The level of correspondence increased after Lord Byron left England to live on the Continent following the breakdown of his marriage. Kinnaird acted as agent and power of attorney for his friend, which necessitated him becoming very involved in the business and private affairs of the poet. As such, their correspondence forms a significant and important source for information about the life and affairs of Byron and his circle because they candidly cover matters of personal interest, gossip and business activities. The letters span the last decade of the life of the poet and cover the period when some of the most important works of Lord Byron were published, including 'Don Juan'.