It definitely is a painting because it has texture, it is probably just my low resolution camera-phone filtering out the finer details. Also, the painting hangs in the dark corner of my Nan's dining room, apparently to keep the paint from fading, so perhaps its dark location contributes to it appearing blacker or darker than it actually is.
My Nan told me that it was a private commission, painted by an amateur artist friend of the subject. At least that is what she was told be her father (my great-grandfather) anyway...
My Nan has apparently named me as the beneficiary of this painting in her will, so at some point in time I will have ample chance to discover more about its origins, but in the meanwhile I am interested to read the various opinions here.
Reading these replies so far, I am leaning toward it being my 4xgreat-grandfather (1832-1904).
He was the first generation to move to Bath in 1850, aged 18 similar to the subject, and the family have lived in Bath ever since.
Many thanks, Paul