Ashurst is on track to miss a key gender diversity target for 2018, with the proportion of female equity partners at the firm lagging significantly behind its target figure of 25%.

The firm unveiled a series of targets in 2014, including an ambition to have women make up one quarter of the equity by 2018.

However, only 15% of the firm's current partners are female – far below the firm's stated goal.

Ashurst's ability to hit this target will have been affected by this year's promotion round, when it made up four women in a 19-strong haul. This equated to 21% of the promotions, despite a stated 2014 target to have women make up 40% of new partner promotions going forward.

On average, 32% of the firm's new partner promotions during the past five years globally have been female.

However, Ashurst has achieved one of its 2014 ambitions. The firm set out to have a quarter of all of its management positions held by women by 2018 and has already surpassed this target for wider management positions.

While its managing and senior partner are both male, 30% of the board is female and 41% of committee roles are held by women.

Taking into account all leadership roles, including practice heads, sector heads and office managing partners, Ashurst said 21% of such posts are now held by women.

Ashurst head of diversity and inclusion Deborah Dalgleish said: "We know we will not meet all of our targets next year but this has only renewed our determination to move the dial. The exercise has resulted in a continued focus on the relevant areas, flagging awareness of particular issues of concern and promoting consideration of what is needed to address those areas.

"We have made progress while remaining keenly aware of how far we, and much of the sector, has to go. Diversity and improving gender balance are a critical part of our business."