The British journalism industry was found to be 94 per cent white and 55 per cent male, with almost all ethnic groups significantly under-represented, according to a survey carried out by City University London.
"This under-representation is even greater when you consider where journalists work – over a third of journalists work in London and there is a higher ethnic minority workforce there than in the rest of the country," said Thurman.
"While diversity in British journalism has improved in some respects, there is still some way to go and there are some worrying trends for the future."
The study surveyed 700 news professionals in the UK over four main areas: gender equality, education and religious and ethnic groups.
It found that women remain underpaid, with 50 per cent of female journalists earning £2,400 or under a month, compared with only a third of men.
Taking into account the age of the journalists and their subsequent amount of experience, the survey found that women were also less likely to be promoted to senior positions than men.
Some 64 per cent of men with six to ten years experience in the industry had been promoted into junior or senior management positions whilst 50 per cent of women remained in less senior positions.
"These differences in seniority may help explain the fact that men felt they had a bit more freedom in selecting and framing the news stories that they worked on," said Thurman.
Current trends show that more women than men are now entering the profession, with 65 per cent of new starters within the last two years being female.
The study also found almost all journalists within the profession with three years of experience or under had a university degree, with over a third having a Masters.
As women continue to outnumber men on university degree courses, Thurman noted that this "academisation" of journalism seems to be positively helping correct the historic gender imbalance in the profession.
But it also might be having "undesirable consequences for the socio-economic diversity of journalism" as people from disadvantaged backgrounds are three and a half times less likely to enter university.
"When we talk about diversity in journalism it's both the make up of the workforce to consider, and also whether then news output reflects the diversity of the audience," he added.
Some major religions, including Islam and Hinduism, were under-represented, with Thurman noting one Muslim decided to apply for jobs with an English-sounding name to get an interview.
Finally, the study asked journalists about how important they felt it was to promote diversity within their work.
The answers were significantly different depending on the role of the journalist and the topic they covered.
"Economy reporters in general didn't feel it was important to promote diversity, but reporters in other areas, for example culture, felt it was more important," said Thurman.
Acknowledging the "system", he explained there are a wide range of factors that could affect diversity within the industry, such as limited resources and commercial pressures.
"Over 40 per cent felt that their freedom to make editorial decisions have decreased over time, which could have an impact on the diversity of news coverage," said Thurman.
"While most journalists see promoting diversity as important, they are part of a system, and with journalists feeling increasingly influenced by audience data, we have a responsibility in the choices we make as consumers.
"With the strengthening influence of PR activity and advertising considerations on journalists work, advertisers and marketers must also take some responsibility for media content."
The full survey will be released in May 2016.