I’ve discovered a colleague who joined two years ago is paid £20,000 more for a similar role. 

My boss says it’s because that’s what it cost to get them to move from a rival company, and they are ten years’ older with higher earnings built up over a longer career. 

We are both women, so there is no equal pay claim, is there any other way I can challenge this?

HR expert Kate Underwood said: The door to an equal pay claim is shut because you are both women.

If the reason for the pay gap is age, it becomes discrimination and your employer has to justify it objectively.

Paying what it costs someone to prise someone away from a rival can be lawful, and employers defend it successfully all the time, but ‘they are older’ is not a market rate.

Additionally, your colleague has only two years’ service. 

If you have been there longer, length of service cannot be the justification, because on that measure you are the one who should be ahead.

I’d advise you to put in a written grievance and quote your boss back word for word.

Ask for the criteria for the pay range for your role and what the £20,000 is actually buying. 

Ignore any rule about not discussing pay with colleagues, because it is unenforceable when you are checking for discrimination.

Watch the clock, too. Discrimination claims usually have to be started within three months less a day.

Glenn Hayes, a partner at Hill Dickson, added: Employers can justify a difference in pay by citing factors other than age, such as greater skills and experience. 

Even when there is no immediate legal claim, employees often challenge pay disparities through a formal grievance, requesting a pay review or citing general unfairness.

A £20,000 gap is significant, and if the employer fails to take steps to address this, it may be that such action (or inaction) could amount to a fundamental breach of contract entitling the employee to resign and bring proceedings for constructive dismissal.