There has been a dramatic shift in representation of women at the highest level of British business, with the number of female board members in the nation's top listed companies increasing by 50 percent in the last five years.

More than one third of board level positions at companies listed on the FTSE 100 and 250 indexes were held by women by the end of 2020, according to the final report of the government-backed Hampton-Alexander Review.

The number of women on the boards of Britain's biggest companies by value, which are collectively known as the FTSE 350, has risen from 682 in October 2015 to 1,026 in January this year, it said. The report also noted that there are now no all-male boards in the list.

The review was launched in 2016 to encourage UK-listed companies to appoint more senior women. The figures also show an increase in women in wider senior leadership roles.

However, the review said that more than 100 companies on the FTSE 350 list are still not meeting the target of having at least one third of board positions held by women, and that "significant progress" was still needed.

The report said: "Moving forward, all businesses should be pushing themselves to move beyond tokenism, and ensure even more women are getting into the highest ranks.

"While women make up more than a third of those in senior leadership positions, the review found that significant progress remains to be made on the highest executive roles, such as CEO."

The 30% Club, which advocates for better boardroom representation of women around the world, welcomed the improvement.

BBC News quoted Ann Cairns, global chair of the 30% Club, as saying: "The Hampton-Alexander Review has played a significant role in bringing about greater gender diversity to the boardrooms of Britain's biggest companies." But she warned that female representation at the top level remained "fragile and slow".

A government minister urged companies to appoint more women to senior executive positions. In a statement, business secretary, Kwasi Kwarteng, said: "FTSE companies have made incredible progress in recent years, but we cannot become complacent in building a society where everyone has an opportunity to get on and succeed.

"The UK government's voluntary, business-led approach to increasing women's boardroom representation has been hugely successful and will, I hope, serve as a blueprint for countries across the world looking to make business more reflective of society."

Review chair, Philip Hampton, said: "The progress has been strongest with non-executive positions on boards, but the coming years should see many more women taking top executive roles. That's what is needed to sustain the changes made."