[2] Platt was active in local politics, taking a leading role in successfully campaigning for Oldham to be incorporated as a municipal borough.

Supporters of the incumbent Radical William Johnson Fox approached both Platt and his brother in 1856 to stand for election, with James accepting.

However, local divisions led to a rival candidate John Morgan Cobbett also standing in the radical interest.

Although Platt was immediately bandaged, he suffered extensive blood loss and, after being moved to his home in Ashway Gap, he died between 14:00 and 15:00.

[5][2] After his death, and although he had only made three contributions to Parliament, Platt was celebrated in the media—including the Manchester Examiner and The Times—as a "rising man" who would have been likely to "distinguish himself greatly".