Studies of the social background of top civil servants reveal a wider basis of recruitment but significantly less than the Oxford survey would suggest. A study by Halsey and Crewe shows that in 1967, only 17% of the higher administrative grades in the civil service were filled with individuals from manual working-class backgrounds.
Thus the Oxford study, while showing a relatively high rate of mobility into class 1, does not indicate the degree of elite self-recruitment. Though class 1 as a whole appears fairly open, elite groups within that class are relatively closed.