This Deceitful Light by Jemahl Evans
In a time of civil war and betrayal, one drunken fop could be the difference between victory and defeat. Sir Blandford Candy is an irascible old drunk with a love of hats, a dislike of poets, and an idiot for a nephew. Resting after blackmailing an old acquaintance, he looks back on his life and adventures during the English Civil War. Young Blandford returns to London after the First Battle of Newbury. He finds a new Lord Mayor in the Guildhall and a murdered actor in his theatre. Blandford tries to foil a Royalist plot to smuggle gold to Oxford, find a sailor's lost treasure, and hunt for a book that could change the course of the war. His search takes him from the dark streets of London and Southampton to the bloody battlefield of Marston Moor, but only one man can help. A man Blandford has sworn to kill. This is the second book in the Blandford Candy series.