British agencies are losing out on global advertising briefs because there are too many white men sitting round the table, according to the industry's leading intermediaries.

Today Creativebrief joined Oystercatchers' commitment to disclosing diversity data from agencies to their clients, following warnings to agencies about diversity in the US by General Mills, MP and Verizon.

All the intermediaries contacted by Campaign, Oystercatchers, AAR, Creativebrief and The Observatory International, said clients did not ask them for agency diversity data at the early stages as a rule. But they would notice a lack of diversity during meetings.

The Observatory's co-founder, Lucinda Peniston-Baines. said: "We will go in to meet them and quite often, we will walk out and more often than you might think, the client will say, 'My brand is a female brand, why have I faced six blokes, or five blokes and one woman?

"It gets sniffed out and rejected on that basis."

She added that The Observatory often encouraged global clients to take briefs to Amsterdam, where agencies boast a more diverse mix of staff.

Martin Jones, managing partner at the AAR, said most brands were currently focused on diversity at their incumbent agencies.

"However, when the review has begun, clients often comment on the domination of 'white males'," he added, recalling an episode where the brand comprised ethnic minority staff of both genders, and one white male. The agency team comprised thirteen white men, and three white women.

"Historically clients have accepted this as 'the way the industry is'," Jones said. "However, diversity in all forms will, and should be, an important factor when considering new agencies."

Intermediaries will disclose agency diversity data

When contacted by Campaign last week, Oystercatchers' chief executive Suki Thompson promised the intermediary would ask for and disclose diversity data on agencies.

Creativebrief has disclosed that it is already working on extracting diversity data on agencies.

Managing director Charlie Carpenter promised the information would be visible to brands on Creativebrief's online agency showcases by early 2017.

"We already ask clients a lot at RFI stage about the profile of their target audiences (gender and ethnicity being a key part), and this very often strays into discussion about how representative of that audience a future agency might be," Carpenter said.

"We are also formalising this by adding a question about diversity into our initial client briefing form, which prompts them to consider this seriously right from the start if they haven't already."

Carpenter added Mother London had won the UN's world sanitation campaign in 2014 over a rival, because the agency had put forward a "globally minded, multi-cultural and gender diverse team".

More recently, he said, three clients had decided not to proceed with agencies because their teams "felt too one dimensional".