All UK companies with more than 250 staff are now required to report data around gender and pay gaps in their organisation.
Of the 19 WPP units (including the holding company itself) with more than 250 staff, the one with the worst median hourly pay gap in 2017 was J Walter Thompson at 44.7 per cent. The holding company is the second worst, at 32.8 per cent.
At the other end of the scale was Kantar Media, with 12.7 per cent in favour of women. The only other that pays women more is Hill+Knowlton Strategies, with a median pay gap of 3.9 per cent. No agencies have a mean (as opposed to median) pay gap favouring women.
Ogilvy & Mather Group has a median pay gap of 24 per cent, while at Y&R Group, which includes Burson-Marsteller, Cohn & Wolfe and Axicom, it was 14.6 per cent. Other agencies, such as Buchanan, Clarion and Finsbury, are not covered.
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The report also includes case studies of a number of eight women in WPP firms, including two senior PR figures: H+K head of business development Sam Lythgoe, and Finsbury head of digital Yim Wong. Another case study is of new UK country manager Karen Blackett, who also provides commentary on the data.
While WPP has a gender-balanced workforce of 51 per cent men and 49 per cent women, the report said the overall gap is due to fewer women in senior roles, where pay is highest.
Blackett writes in the report: "WPP does not struggle to attract female talent. We have a gender-balanced workforce and all our companies work hard to ensure everyone is treated equally and has the same opportunities to develop in their career."
Blackett continued: "Nonetheless, in common with the industry as a whole, we need to do more to change the gender profile of our leadership teams if we are to close our pay gap."
To address the lack of women in senior roles, WPP has promised to place greater emphasis on the development of female leaders. This will include: 'actively promoting best practice in recruitment, training, mentoring, parental leave and flexible working within our companies.'
Across the agencies, the company with the fewest women earning a salary that falls within the top quartile is e-commerce specialist company Salmon, which has 88 per cent men in the top quartile. It has an overall median gender pay gap of 23.8 per cent. AKQA is the second worst on this measure.
The agencies with the most gender-balanced ratio in the top salary quartile are H+K (51 per cent women and 49 per cent men), Millward Brown (52 per cent women) and Grey Advertising (55 per cent men). All other agencies have a gap of more than 10 percentage points on this measure.
James Whitehead, chief executive of JWT London, which displays the worst pay gap, said: "These numbers are obviously disappointing and we are determined to improve them. Where we've given real focus with initiatives over the past 18 months, we've seen real change in attracting great young female talent into the agency."
This story uses excerpts from a piece originally published on PRWeek sister title Campaign