As parliament started to wind down today ahead of the Christmas break, MPs gathered for a progress report from the working group on bullying and harassment. It was set up in the wake of reports that underscored what many of us have been shouting about for a long time: serious sexual harassment and bullying is endemic in Westminster.

The scale of the task at hand has been, at times, overwhelming. Those of us sitting on the working group have had to grapple with putting in place a policy and procedure to tackle a wide range of behavioural misconduct across the parliamentary estate and in constituency offices, from sexual harassment of House of Commons staff by MPs to harrowing accounts of sexual and other forms of assault. A member of my own staff has experienced racial harassment from a staff member in a neighbouring office, while journalists like Kate Maltby have come forward highlighting inappropriate behaviour by MPs, peers and those in positions of power.

The majority of the working group have backed the principle of mandatory training for MPs and peers

Things are shifting, and Damian Green’s forced resignation is evidence that the immunity once enjoyed by the very powerful and influential is starting to wear off. The prime minister deserves credit for walking the walk, but we are still lacking a system which delivers justice for complainants or confronts the underlying causes. It’s essential that we come up with a set of recommendations to tackle the broad spectrum of misconduct, while at the same time recognising that systems alone are insufficient unless we also change the working culture to one of zero tolerance. This task is not without its challenges, but we have taken some important steps forward and laid the foundations for more long-term change too.

I was able to secure an advisory role on the working group for one of the country’s best qualified experts in sexual harassment, which meant potential battles over the critical principle of having separate sexual harassment, and bullying and harassment, policies and procedures were quickly won. I would like to pay tribute to colleagues who listened to the evidence and, in many instances, have been on their own journey of understanding around issues such as consent, survivor-led best practice and anonymity.

All political parties need to grasp that abuse and harassment are not party-political issues. It has been apparent from the outset that responsibility for harassment allegations should not be handled exclusively by those with a vested interest in protecting their own political party.

No political party is perfect, and I am certain that the Green party will have its own ongoing questioning and learning to do, as confidence in procedure and a more vocal discourse on harassment encourages people to come forward. The challenge for all political parties is to be brave enough to accept that a culture of harassment can change if we want it to, that no one is exempt, and that we must prioritise the voices of those coming forward over party reputation. This starts with a robust, independent process and support structure for those who want it – and I am disappointed that we have not been able to announce cross-party support today for the full extent of what that should mean.

The majority of the working group have backed the principle of mandatory training for MPs and peers, that we need a new behavioural code with sanctions that could include recall in the most serious cases, and that historic cases cannot be ignored. The report we have produced isn’t perfect, but it represents a huge step forward and, frankly, is little short of a miracle given the timescales involved. It’s vital that its recommendations are given urgent consideration by parliament as soon as possible.

That matters hugely to those individuals who deserve their complaints to be heard and to be supported through that process. And it matters too because a seismic cultural shift is needed in parliament – and until that gets under way, more individuals are at risk and more will get away with unacceptable behaviour. It is vital that MPs have mandatory consent training from specialist advisers, something I have pushed for since allegations first came to light. Only then will MPs fully understand the power that they hold and the weight of their actions.

While the working group has agreed that consent training should be given to all MPs following the next general election, this could be as far away as 2022. My own view remains that it should be given to all MPs immediately, with financial penalties imposed on those who fail to cooperate, as has been recommended by the public administration and constitutional affairs committee. Staffers and visitors to the parliamentary estate cannot afford to wait another five years for safety in the workplace.

Colleagues on the working group are wholly committed to driving things forward, ensuring staff are full partners in the process and remaining engaged in the process of meaningful change. I only hope that, at this crucial junction, we do not sacrifice the rights of those speaking out and coming forward about the abuses they have experienced at the altar of party politics. There is only one reasonable objective – a safe, respectful, working environment for everyone.

• Caroline Lucas MP is co-leader of the Green party and is on the cross-party working group on sexual harassment in Westminster