Some more records by piano player Jan August have turned up, that have the same picture on the cover that was the source of Warhol’s drawing for the Progressive Piano cover. They are all on the Mercury label, but were issued in three different continents.
US EP with four tracks taken from the 1955 album ‘Jan August Plays Songs To Remember’.
English EP, supporting 4 tracks from the album Music For The Quiet Hour (1955). This EP was issued much later though in the UK, cover says “Recording first published 1958”
In Australia the album ‘Jan August Plays Songs To Remember’ was released with (nearly) the same image in colour. It seems to be a different, painted version, not a picture. The cuff link and shirt sleeve for instance are very different.