The external examiner plays an important role in all degree level examinations in higher education in the United Kingdom. The external examiner system originated in 1832 with the establishment of the University of Durham, the first in England since Cambridge was founded 600 years earlier. Durham used Oxford examiners to assure the public that its degrees were a similar standard to Oxford's. The establishment of more universities in England from the 1880s was accompanied by a requirement that examinations be conducted by internal and external examiners. It is also found in countries whose higher education systems were developed from United Kingdom practice, or strongly influenced by it, after its introduction, including New Zealand, and India. It is one of the oldest systems of quality control within higher education.

It is a requirement for all degree level examinations at British universities, and in countries operating a similar system, that at least one member of the examining board should be from a university other than the one awarding the degree (and should have no recent affiliation with it). This applies both to undergraduate examinations, where there may be hundreds or even thousands of candidates, and to postgraduate examinations including those for the PhD where a special board is convened for each candidate.