He means that while there were cases of abuse, it was not always the case.
Explanation:
According to Edward Baines in his book "History of the Cotton Manufacture in Great Britain", he acknowledges that people claim there are cases of maltreatment of children who worked in labor mills, but he believes that those cases are not the general truths for workers in factory mills.
He makes this statement based on the findings of Factory Inspectors who visited "nearly every mill in the country" and found out that the claims of maltreatment "contain a very small portion of truth".
