Revealed: Glass ceiling in Scottish universities

The figure is just over three percentage points better than the situation in 2010/11 when 18.3 per cent of professors were female.

While direct comparisons between universities are difficult to make because of the different disciplines they offer, some institutions have particularly small proportions of female professors.

The lowest is Abertay University, in Dundee, where seven per cent of professors are female, followed by Heriot-Watt, in Edinburgh, with a proportion of 15 per cent.

Queen Margaret University, in Edinburgh, has the best record on female equality with 40 per cent of its professors female.

Linda Somerville, project director of Equate Scotland, an organisation dedicated to the advancement of women in science and engineering, called for a change of culture across the sector.

She said: "These figures comes as no surprise and we know the proportions in some disciplines such as science are even lower.

"There is something going on within institutions that mean women leave in much higher numbers and don't progress their careers in the way that their male counterparts do."

Ms Somerville said there were a variety of barriers reported to Equate Scotland, which is based at Edinburgh Napier University and funded by the Scottish Government.

These include a culture of long working hours, inflexible terms and conditions and pressures on researchers to produce academic papers which can be incompatible with family responsibilities.

She added: "Many universities use short fixed-term contracts which can deter women because of the lack of security and we also see an indirect sexism where male professors can almost subconsciously mentor and promote those that are similar to themselves."

Mary Senior, Scotland official for the UCU union, which represents academics and support staff, said the figures highlighted the glass ceiling in higher education.

She said: "It is a real concern that progressing to the top of academia does not seem to be compatible with having children and balancing family and caring commitments.

"We desperately need to address the long hours culture and pressures to churn out publication after publication if this is to change."

Vonnie Sandlan, women's officer for student body NUS Scotland, said the latest "worrying" figures proved gender inequality was still a serious problem within higher education.

She said: "In too many institutions, across too many subjects, women continue to face significant barriers which mean that in terms of seniority, job roles and representation, women fall far behind their male counterparts.

"Our universities should be leading the way on equality, yet these figures evidence a need to seriously address the issues of gender inequality within higher education."

Ms Sandlan also called for the way research funding was allocated to change to take account of more flexible working practices.

Universities Scotland, which represents university principals, said the issue of gender equality was a matter of concern for institutions.

A spokeswoman said: "Just as with other organisations, and society as a whole, the gender balance of university staff is not equal at all levels or in all fields of study, but this is something universities are very aware of, are closely monitoring as part of their equality duty and are working hard to redress.

"Universities are part of important schemes like the ATHENA Swan and Equate Scotland which support the career progression for women working in the sciences and maths as female representation has typically been lowest in these areas.

"These efforts are paying off with a gradual year-on-year increase in the proportion of female professors in Scotland since 2010 with an average one per cent increase each year during this period."

Across Scotland there are 2,275 professors, but only 495 are female, amounting to just 21.8 per cent. At the present rate of progress it would take at least two decades to achieve equality of gender in promoted posts.