Close to this plaque is a much larger and much more informative one mentioning the Salford MP's concern for the abolition of child labour, better education, health and nutrition. He established the first vegetarian soup kitchens and was the founder of the Vegetarian Society in 1847. Some of these things (and a few others) I mention in my blog post on Brotherton's memorial in Weaste Cemetery linked below.
The statue, appropriately, is on the Salford side of the River Irwell. Directly opposite it on the Manchester side is its former site in Albert Bridge Gardens. Originally it was in Peel Park in Salford, by was taken down in the 1950s to make way for a college, then bought by the owner of Gawthorn Hall in Cheshire in the late 1960s and then bought back by Manchester City Council. Perhaps the Brotherton statue has now found a permanent home.