Photography technology good enough to create a lasting image did not exist before about 1840. Anything created before this date was with a "camera obscura" and would have faded soon after. A camera obscura image required several hours of exposure. Even though William Abney died in his late 80's according to the dates on this site, he would have been older than the man pictured here. He would have been 88 when he died.
Even in 1840, camera technology was in its infancy, and lasting images of any kind, including a daguerreotype would have required an exposure time of considerable time, over 30 minutes at the very least. It would have been nearly impossible, even with devices such as "head clamps" to get a clear, sharp images such as this one. Photography technology was advancing fairly rapidly, and by the beginning of the Civil War, photographers were much more common -- so common that they could not sell all the images they took during that conflict. Still, at that time photography was cumbersome, and required making negatives on plates of glass just prior to making a photograph. Simply put, it was a time consuming affair requiring a huge amount of equipment including horse drawn trailers that served as a "portable" dark room to process the images.
And so, in the early 1840's photographers would have been very few in number indeed. So, while William Abney may have looked similar to the man pictured, it is almost certain not of him.
