FTSE 350 companies that added women to their boardrooms this year include international distribution and outsourcing group Bunzl, which appointed Eugenia Ulasewicz as its first female director, and plumbing products firm Wolseley, which appointed Tessa Bamford as its first female board member.

However, Cable and May said that there was still more that could be done.

"We would encourage you to build on this by setting and developing targets and strategies, in order to effect the necessary change through means best suited to your own circumstances," the letter continued.

Lord Davies will be meeting with his steering board later this year to analyse the progress made on his recommendations, and will continue to report on the progress annually.

The reminder follows the recent launch of a , which aims to encourage head-hunters to promote gender diversity at boardroom level.