A Queensland mining company paid its workers to attend a protest against state water licensing reforms, directing farmers on its staff to don checked shirts and Akubras to illustrate the spread of community support for the company.

New Hope Group ran its New Acland coal operation with a skeleton crew while transporting the rest of its rostered workforce by bus to the rally outside parliament in Brisbane on 1 November.

The company’s efforts have been in vain, with Palaszczuk government legislation passed on Thursday opening up a future water licence for its contentious Darling Downs mine expansion to public submissions and legal appeal.

Labor, with the support of independent MPs, voted down amendments sought by the Liberal National opposition to shield New Acland from a court challenge to its licence.

An internal company email seen by Guardian Australia shows how the company marshalled its workforce to gather maximum protest numbers in a bid to drive home its message to the government that future legal challenges could jeopardise 700 jobs at the mine.

The email from the New Hope Group managing director, Shane Stephan, included specific instructions about what to wear to the rally.

“If you are a farmer please wear your check shirt and Akubra – everyone else is asked to wear their hi vis shirts,” Stephan wrote.

The impact of New Hope’s proposed expansion on prime farming land and groundwater is a major point of contention in a current land court challenge brought by a group of local landholders.

Farmers feature prominently among that group, the Oakey Coal Action Alliance.

Stephan told Guardian Australia that New Hope had “quite a large group of farmers – about 45 – that supplement their farm income with their wages form working at the mine”.

“I think it’s important that the public understand that not all farmers and landholders around the Acland mine are opposed to the Acland stage-three project, which is sometimes a line pushed by the project’s opponents,” he said.

New Hope decided to keep on a skeleton crew to maintain “critical activities” at the mine on protest day while arranging buses from three locations to take staff and their families to parliament.

Stephan said in the email: “All other rostered employees (day, afternoon and night shifts) will be expected to attend the activity in Brisbane as a rostered day – i.e. if you are rostered to be at work (and are NOT part of the skeleton crew) we will pay you to attend Brisbane.

“Employees not rostered to work will be asked to show their support by attending.”

Rally organisers released a protest song to the tune of Bob Dylan’s Blowin’ in the Wind.

It included the lines: “Why are the green voices worth more than mine / than my son’s, my daughter’s, and my wife’s? Oh and why should some city slickers ever have the right/ of ruining the future of us all?”

Adani was spared the prospect of facing future legal challenges to water licences for its Carmichael mine after the government passed amendments exempting projects that have already received a land court ruling.

Hearings in the land court challenge to New Acland’s environmental and mine licences are complete but the member is yet to hand down a judgment.

Stephan in a statement on Thursday said the laws were likely to destroy the livelihoods of hundreds of people by opening up more hurdles for was “ without doubt the most scrutinised mine in Australian history”.

The company now expected another 12 months’ delay in gaining approval, he said.

Stephan complained that the company had “clearly presented the impacts of this legislation to [environment] minister [Steven] Miles. Either he wasn’t listening or he just doesn’t care.

“New Hope Group lodged the original application for stage three [its expansion] in 2007 and has been battling green lawfare ever since.”

Stephan said New Hope supported the objectives of the laws but did not want to “needlessly repeat” studies if underground water impacts.

Lawyers for OCAA in the land court case have argued that New Hope’s modelling of groundwater impacts at the New Acland mine is so unreliable that it should recommend refusal of environment and mining licences.

The case has also seen the company’s own expert revising job creation figures down from 2,953 a year to 680 net jobs nationwide.

Lawyers for OCAA also question the public benefit of a project that would see an estimated $500m royalties would flow back to the company and a handful of property owners, not to the state, because of a legal loophole.

In the email to staff, Stephan credited the “volume of submissions from supporters of [New Acland Coal] highlighting the impact that this legislation could have on their jobs” for prompting a parliamentary committee to direct Miles to report back on the impact on miners’ short term operations.

“Your voice is being heard and we need to ensure that all of our voices continue to be heard loud and clear,” Stephan wrote.

“In order to assist minister Miles and the premier to understand the immediate impact that this legislation presents to NAC and therefore all of us we are seeking as many employees and supporters as possible to join us at parliament house on Tuesday 1 November.”

After the protest, the company gave its workers a barbecue lunch in the Brisbane Botanic Gardens.