The Universities of Durham, Exeter and York, and Queen Mary, London, have accepted their invitations for membership in the association of prestigious British higher education institutions.

The addition of the four new members, which was announced by the Russell Group this Monday, 12 March, brings the member total of the Group to 24.

In a statement that came with the announcement, Prof. Michael Arthur, Chair of the Russell Group, said that the four new members “Have demonstrated that- like all other Russell Group members- they excel in research, innovation and education and have a critical mass of research excellence across a wide range of disciplines.”

The mention of “a critical mass” by Prof. Arthur suggests that the universities were recruited primarily to fulfill one of 8 objectives identified on the Group’s website, specifically that funding is steered by the Group “to where a critical mass of research can be undertaken to ensure the highest international standards with the greatest impact.”

Another stated objective on the Group’s website suggests that it defines the impact of research as “benefit for the UK economy and society, through the commercialisation of innovation and the exchange of knowledge and ideas.”

Queen Mary was the only institution ranked within the top 20 for private research income that was not included in the Russell Group until it joined the Group on Monday, according to the latest 2009-10 financial year figures compiled by Times Higher Education.

However, the Universities of Aberdeen and Dundee as well as the London School of Hygiene and Tropical Medicine (LSHTM) all received more private research grant and contract income than York, the second-highest earner among the new Group members.

The choices of addition to the Group may be seen as an attempt to balance the desire for highly commercialised research among Group members with the desire to include institutions in which “teaching of the highest quality takes place,” another stated objective of the Group.

Both the overall Independent and Guardian league tables, which focus mostly on teaching quality, rate Exeter, Durham and York all several notches higher than Aberdeen and Dundee, while LSHTM is a research-centered institution that is not ranked in either table.