The last Cabinet Secretary to not attend college was Robert Armstrong, Baron Armstrong of Ilminster. He served as Secretary to the Cabinet from 1979 to 1987, under Prime Ministers Margaret Thatcher and James Callaghan.

Armstrong was born in 1932 and grew up in a working-class family in Somerset. He left school at 16 and worked as a clerk in the Civil Service before joining the Ministry of Defence in 1955. He rose through the ranks of the civil service, and in 1974 was appointed Permanent Secretary to the Department of Employment.

In 1979, Armstrong was appointed Secretary to the Cabinet by Margaret Thatcher. In this role, he was responsible for providing administrative support to the Cabinet and advising the Prime Minister on a wide range of policy issues. He was also a key figure in the Northern Ireland peace process.

Armstrong retired from the Civil Service in 1987 and was subsequently appointed to the House of Lords. He died in 2003 at the age of 70.

Armstrong's lack of a college education was not unusual for Cabinet Secretaries in the past. In fact, up until the early 20th century, it was not uncommon for Cabinet Secretaries to have no formal education beyond elementary school. However, as the educational attainment of the population as a whole has increased, so too has the educational level of Cabinet Secretaries. Today, it is almost unheard of for a Cabinet Secretary to not have a college degree.

There are a few reasons why Armstrong's lack of a college education is notable. First, it shows that he was able to achieve a very high level of success in the Civil Service without the benefit of a traditional university education. Second, it suggests that the Civil Service was once more open to people from all walks of life, regardless of their educational background. Finally, it provides a reminder of how much the world has changed in terms of educational attainment in the past few decades.

In conclusion, Robert Armstrong was the last Cabinet Secretary to not attend college. His lack of a college education was not unusual for Cabinet Secretaries in the past, but it is now very rare. Armstrong's success in the Civil Service shows that it is possible to achieve a high level of achievement without a traditional university education. However, the world has changed a great deal in terms of educational attainment since Armstrong's time, and it is now almost unheard of for a Cabinet Secretary to not have a college degree.