we don't have recordings of people's accents before the late 19th century, and even then the few famous recordings (e.g. Gladstone) are of uncertain veracity. Prior to the 19th century, a person's social status could be assessed instantly from their dress. Moreover, Public School and University education was less universal among the ruling classes than was the case later. Accent as a social diagnostic would have become more important as the Industrial Revolution made cheaper clothes more widely available- exactly the period of Peel's youth. Since Robert Peel went to Harrow and Cambridge, you can probably assume he was a fully housetrained toff despite his rather infra- dig commercial background.