The fact is that we do not know why Aitken became passionately pro-American. There was no inkling of this during his days in America. The timing of the revolution was as big a factor as any, with the war becoming news in England just as Aitken’s life had hit rock bottom. Even so, he was not an immediate convert. The war had already started by the time he returned in 1775, and for several months, he wandered aimlessly, becoming more reckless with each passing week. This much is clear: before he embraced the American Revolution, his wanderings had no purpose; after he embraced it, they did.

At some point, presumably toward the end of 1775, his thinking progressed from favoring the American Revolution to wanting to play a part in it. This was a step that other British radicals, Price included, were not willing to take. It did not occur to Aitken that he might be able to do something on his side of the Atlantic until he overheard an otherwise innocent conversation. “It is amazing with what force this conversation kept possession of my mind,” he was later quoted as saying. “I believe it never left me afterwards.”

The circumstances were harmless enough. Several men were gathered in a public house in Oxford, talking about the war. Aitken hung on their every word. The Royal Navy, they all agreed, depended on the royal dockyards; take away these, and the war was as good as lost.41 The conversation’s effect on Aitken was electrifying. It was then and there that he set himself the task of hobbling the Royal Navy by destroying the dockyards that kept it afloat.

It was an ambitious undertaking, especially for just one man. But therein lay its appeal. It gave him a challenge. The destruction of just one dockyard would prove an enormous undertaking, one that would use all his talents. The skills that he would employ were the skills that he already had, starting with the two things he had learned as an apprentice: how to draw and how to grind colors and mix paints. He would use the first in making elaborate sketches of his targets, along with designs for incendiary devices, and he would use the second in manufacturing his own combustibles. He was forever grinding unlikely substances, often prevailing on unsuspecting painters to lend him their stones. His background as a painter probably explains why he favored turpentine over other combustibles. The skills that he had acquired as a burglar would also serve him well, allowing him to move about without drawing attention to himself, slipping in and out of buildings and storehouses. It helped, too, that he was the sort of man whom nobody seemed to notice anyway.

His expectations soon acquired a life of their own, and he started to become slightly unhinged. He relived the same scenario, again and again: with the dockyards destroyed, America would win the war by default, and he would return there an officer and a hero. The indignities, obscurity and crushing commonness of his past life would all be behind him.

There was a caveat. Although he desperately wanted fame, he did not want to work too hard or long to achieve it. In this we can detect the impatience and impulsiveness of a very young man. From this perspective, he had come up with just the right project. It was nothing if not economical of his time, with ten months all told for gathering information, and perhaps two months, if everything fell into place, for burning down each of the major dockyards: Portsmouth in the southwest, Plymouth in the west, and Chatham, Woolwich, and Deptford outside London.