I work in HR and feel very strongly that parity of role / outcome deserves parity of pay when all things are equal. It's not clear if another woman on your team also had higher pay, or if it was just men. In some countries, employment law come out very strongly on the side of the employee. The UK is not one of those countries.. you only have to look at the gender pay gap to see inequity is happening all the time; and there is little that can be done to 'compel' changes in this regard. I'm not aware of any legal requirement to pay back pay unless say the payroll messed up and paid you wrong. Contractually, you're entitled to that back pay.
Your increase may bring you in line but this is different to saying you now earn the same as they do. You could ask for back pay and make a reasonable argument if you have all been at the company the same length of time, have the same qualifications, have the same experience etc (all valid data points when it comes to defining base pay). It would be rare to have 3 employees on one team who are literally carbon copies, there is usually some differentiation.
If you do go for it, or raise a grievance, be prepared to evidence that you are a carbon copy of your peers. That isn't always easy. Bear in mind you're also inviting your employer to find reasons to justify your different salary to date.
In my experience the best you'll get is a back date to the most recent point this year where the typical annual salary merit increases are done or you could argue for 1st Jan if that's earlier. Otherwise you're essentially disputing potentially years of salary decisions and asking for each one to be assessed. Remember, if you get back pay, you'll have to pay back tax and NIC. Make sure it's worth your while, i.e. you'll get a meaningful net amount in pocket.
I've seen many argue this point, and fail. I'm not trying to dissuade you, I actually fully agree with you, but wanted to offer an objective view from the other side of the fence.
Good luck!!