Along with a number of other workers, McLachlan engaged in a protest at the failure of the company to provide the laundry service and work uniforms it was legally obliged to provide, Maher said in a letter to the South32 board. 

“The protest occurred for a matter of minutes and did not result in any lost time or any impediment to coal production,” the letter reads. 

“The company has since fulfilled its obligations in respect of the uniforms.

“At the time of the protest local management did not engage in, or foreshadow, any harsh response.”

Maher said it appeared the company dismissed McLachlan because of his role in the union.

“This harsh and disproportionate action by South32 has already caused significant reputational damage to the company in the local region,” he said.

“As a clear cut case of workplace mistreatment, this matter will not die down or go away, it will spread and do further damage to the company’s standing and prospects.”

A South32 spokesperson told Australia’s Mining Monthly: “South32 takes the matter of workplace safety very seriously and has continued to provide all employees the clothing and PPE [personal protective equipment] required for their job. 

“The company acknowledges the delay in providing the laundry service and has paid employees compensation for that delay.

“Not only was the protest deemed as unprotected industrial action in accordance with the Fair Work Act but it involved people presenting for work inappropriately dressed which is not acceptable in the workplace. 

“Behaviour of this nature does not live up to our values or our commitment to creating an inclusive workplace for all.”

In regards to McLachlan, the company said: “As this matter is before the Fair Work Commission, we will respect this process and do not intend to comment any further”.