Societies worst punishment is exclusion and incarceration

Since the UK hasn't hanged anyone for a long time the worst punishment is incarceration. Imprisonment removes the person from society and takes their liberty.

Other punishments exist. A criminal record. In practice this excludes a person from many areas of employment.

There is also the exclusion caused by debt and bankrupcy. Financial exclusion and the prison of poverty.

Those punishments are the worst that just society will do to an individual.

And then there's the lives of the mentally ill. These punishments can be daily life.