Labour is calling for urgent action to improve the gender mix at the top of the civil service after highlighting that the most senior committee in Whitehall has more members who are knights than women.

The party is calling for the new permanent secretary for the trade department, Antonia Romeo, to be given a place on the civil service board, which describes itself as the highest level of governance in Whitehall.

The group, which is made up of 12 of the most senior officials in government and chaired by the Cabinet secretary, Sir Jeremy Heywood, includes three women and four men who have been awarded knighthoods.

Paula Sherriff, shadow minister for women and equalities, said the situation was unacceptable.

“It just isn’t healthy for government to be run by a narrow, closed circle. We cannot hope for government policy to take into account the diversity of the British public if people making decisions all went to the same schools and universities and come from similar backgrounds,” she said.

“When ministers have appointed more knights of the realm than women at the top level of government, it doesn’t say much for the Tories’ record on equal opportunities.”

Labour also criticised a decision by David Cameron to give himself more power in choosing appointments, arguing that he replaced nine of the most senior women with men during his tenure.

Those decisions took place in a number of leading departments including defence, climate change, the environment, health, the home office, justice, international aid, transport and HMRC.

According to the government’s website, the civil service board also has a subcommittee on corporate management that boasts more people called Mark than women – although its makeup could be even less representative than it appears.

The webpage lists Lin Homer as the one female member but given that she has now retired from her role at the top of HMRC the grouping may now be 100% male.

However, a third committee dedicated to “people-related issues” does have a better gender mix, with eight female members making up more than 50% of the total.

Labour put together a series of written answers and research to show that the problem is wider than just the most senior civil service boards.

They say gender diversity at the top of government has gone backwards under successive Conservative governments, with the number of women holding the most senior post within a department falling by half in five years.

Sheriff argued that Theresa May’s shakeup of government had provided the opportunity to shift the dial, but for the new Brexit department she chose a man, Oliver Robbins, although she has she chosen Romeo for trade.

In 2011, a woman was in charge in half of the top 16 government departments, while now – even with this week’s appointment – the number is just four.

However, the government claims there are other senior positions that it considers to be at permanent secretary level, including “second permanent secretary” and roles such as the chief medical officer.

Taking that into account means they can point to eight women in top positions, with the numbers rising to 10 with Romeo and Shan Morgan joining next month as permanent secretary for the Welsh government .

A Cabinet Office spokesperson said: “The civil service is committed to being a place where everyone can thrive regardless of background, with the aim to become the most inclusive employer in the UK.

“Currently, over 40% of the senior civil service are women. But there is still more to do, which is why we are determined to build on our progress to date by removing any remaining barriers for women and other underrepresented groups in the civil service.”

Labour was also critical about public appointments, arguing that the government’s claims of success in representation in this field is largely down to progress within the NHS. They said only six women were appointed to chair a nondepartmental public body last year, compared with 26 men, rising to 17 women for all bodies, compared with 53 men.

The figures were also low for appointments of people from ethnic minorities and with disabilities. This comes after accusations that May was changing the rules on public appointments to make it easier to pick political allies for senior jobs.

“The prime minister’s power grab will only make things worse if there isn’t a fundamental change of attitude,” Sheriff said.