A group of advertising executives claim they were made redundant for being ‘white, male, straight and British’.

The men lost their jobs at J Walter Thompson after creative director Jo Wallace announced she wanted to ‘obliterate’ the firm’s Mad Men-style reputation.

The men are said to have approached lawyers about the possibility of bringing a discrimination case on grounds of gender, race, nationality and sexuality.

Jo Wallace, pictured, wanted to change the culture of advertising agency J Walter Thompson

If their complaint goes to court, it will become a test case at a time when employers are trying to close gender wage gaps. JWT has one of the most unequal salary structures in the advertising industry, according to data released under government rules. The unidentified executives are understood to have gone to their HR department with concerns about how the drive for diversity would affect their career prospects.

Miss Wallace is founder of Good Girls Eat Dinner, a series of networking events which describes itself as providing ‘inspirational, kick-ass female role models across the creative industries (where they are sadly lacking)’. She has described JWT’s poor performance in the gender pay league as a much-needed ‘rocket’ to address the lack of diversity among senior staff.

After the pay gap figures were published JWT implemented a plan to increase diversity through methods such as ‘unconscious bias training for staff’ and a ‘blind recruitment policy’ which would see details such as gender removed from job applications.

The male-dominated world of advertising is epitomised in the US TV drama Mad Men which portrays sharp-suited, smooth-tongued executives plying their trade on New York’s Madison Avenue in the 1960s.

Gender pay gap figures released in April show that almost eight in ten companies pay men more than women. It found that men also get higher bonuses.

Miss Wallace, who introduced herself as a gay woman at a recent Creative Equals conference, is a high-profile diversity campaigner who has pushed for women to obtain senior positions in advertising.

Miss Wallace said she wanted to change the agency's Mad Men 'male pale and stale' image

In an article last December she wrote: ‘A hell of a lot of people are literally sleeping on the job when it comes to diversifying their creative department beyond white, pale, stale males.

‘There are still far too many creative departments with zero female or black and minority ethnic creatives.’

A JWT spokesman said: ‘It’s not appropriate for us to comment on individuals in an ongoing process. Any redundancies at JWT London are handled fairly, lawfully and without any form of discrimination.’

Aston Martin, Shell, Nestle and Debenhams are among the firm’s clients.