Figures released last week by the Office for National Statistics (ONS) show that the wage gap between men and women increases dramatically between the ages of 30 and 50.

The statistics showed that men and women earned comparable wages throughout their teens, their 20s and early 30s in 2013, but that men started to earn more than women in their mid-30s with the difference peaking at 45 per cent for 49 year olds.

The ONS publication also revealed that in 2013 the highest earning men were 50 years old, earning on average £15.54 per hour while the highest earning women were 34 with an average hourly wage of £13.19. In 1975 the highest earning men were considerably younger at 38 while for women the highest earning group was 25 year olds.

Overall, the difference between the average pay for men and women has decreased dramatically since 1975. In that year, 16 and 17 year old men and women were paid similar wages. Men then earned more than women at every age group after that, with the biggest difference of 61 per cent occurring for men and women aged 38.

The ONS attributes the reduction in the pay gap to employment law changes such as the introduction of the Sex Discrimination Act 1975 and shifts in the wider economy such as the rise of the service sector (which employs more women) and the decline in manufacturing and mining (which historically employed more men).

But why have things improved for younger women as opposed to those in their 30s and above? The ONS speculates that changes to the economy and to legislation have fed through to new entrants to the labour market more than existing members. If that assumption is correct, it anticipates that differences in gender pay at older ages will decrease as time progresses.

It also points out that the percentage differences do not take account of the different types of jobs done by men and women, with women far more likely to work part time. Men are also more likely to work in skilled trade jobs whereas women are more likely to work in administrative and caring occupations which are typically not as well paid.

Emma Game of Thompsons said: “Whilst it is a positive step that the difference in average pay has decreased since1975, the results show that more still needs to be done to address the imbalance. There is still a distinct gender bias meaning workers’ wages should be a priority for the Government to consider.”

To access the report, go to: http://www.ons.gov.uk/ons/dcp171776_368928.pdf