Barnes & Noble rare & second-hand books lists a Sir Charles V. Stanford by John F. Porte. It was published in London in 1921, which sounds the correct time frame W. M. Letts. It's listed as: "154pp. 8vo Black & white frontis photograph + occasional musical notation. Blue cloth. Title page lightly yellowed by frontis tissue guard, binding a bit stiff."

So you ought to be able to get more on both of these from a library.

Good luck.

Sarah