Decades of correspondence between Agatha Christie and her publisher, Billy Collins, have been released and placed in HarperCollins’ newly established archives in Glasgow.

The letters highlight their disagreements over titles and cover designs, despite their long-standing professional relationship.

One letter from February 1946 shows Collins attempting to persuade Christie to accept the cover of The Hollow, writing: “My Dear Agatha, I am so sorry that you do not like the jacket. We all…