The plan to force larger employers in England, Scotland and Wales to publish what they pay men and women in bonuses is a good idea as part of new legislation aimed at reducing the gender pay gap. But 40 years after another significant piece of legislation, the Sex Discrimination Act, the pay gap is still large and persistent and it will take more than publishing the bonuses at big firms to put it right.

What the UK Government is proposing is a good start at least. From next year, any business that employs more than 250 employees will be required by law to publish the difference between the average pay of their male and female workers. The requirement will then be extended to public sector employers.

Naturally, the rules will only apply to a limited number of employees, but the reform does at least shine a light on one important aspect of the pay gap problem, which is that pay differences tend to be higher at senior levels. Precisely why this might be is unproven, although it may be that senior male managers are simply more likely to reward other men more highly. The new rules will not change any of that overnight, but, by making the differences public, they could change behaviour in the longer term.

Firstly, the pay gap is not just about high pay and bonuses – it is about low pay too. Not only are women more likely to be in jobs such as caring, catering and cleaning that are less well paid than traditionally male jobs such as construction, they are also more likely to work part-time and make up the majority of people earning less than £7 an hour. A new minimum wage of £9 is to be introduced, but it is still five years away and in the meantime, the cuts to tax credits will only make matters worse.

There are many other issues that need tackled to fix the pay gap. For example, women often find they are penalised for taking time out to have a family, which is borne out by the fact that it is after the age of 40 that the pay gap is greatest. They are also less well represented in senior positions in society and the Women's Equality Party, which will be standing candidates at Holyrood next year, is right to raise the issue.

But gender inequality will not be fixed until every aspect of it, at every level of society is tackled. Legislation on bonuses is a step forward, but 40 years after the Sex Discrimination Act, the pace of change must be quickened.