The distinction between a county for purposes of the Lieutenancy and a county for administrative purposes is not a new one: in some cases a county corporate that was part of a county was appointed its own Lieutenant (although the Lieutenant of the containing county would often be appointed to this position as well), and the three Ridings of Yorkshire had been treated as three counties for Lieutenancy purposes since the 17th century.
The Local Government Act 1888 established county councils to assume the administrative functions of Quarter Sessions in the counties. It created new entities called "administrative counties". An administrative county comprised all of the county apart from the county boroughs: also some traditional subdivisions of counties were constituted administrative counties, for instance the Soke of Peterborough in Northamptonshire and the Isle of Ely in Cambridgeshire. The Act further stipulated that areas that were part of an administrative county would be part of the county for all purposes. The greatest change was the creation of the County of London, which was made both an administrative county and a "county"; it included parts of the historic counties of Middlesex, Kent, and Surrey. Other differences were small and resulted from the constraint that urban sanitary districts (and later urban districts and municipal boroughs) were not permitted to straddle county boundaries.
Apart from Yorkshire, counties that were subdivided nevertheless continued to exist as ceremonial counties. For example, the administrative counties of East Suffolk and West Suffolk, along with the county borough of Ipswich, were considered to make up a single ceremonial county of Suffolk, and the administrative county of the Isle of Wight was part of the ceremonial county of Hampshire.
The term "ceremonial county" is an anachronism—at the time they were shown on Ordnance Survey maps as "counties" or "geographical counties", and were referred to in the Local Government Act 1888 simply as "counties".
Apart from minor boundary revisions (for example, Caversham, a town in Oxfordshire, becoming part of Reading county borough and thus of Berkshire, in 1911), these areas changed little until the 1965 creation of Greater London and of Huntingdon and Peterborough, which resulted in the abolition of the offices of Lord Lieutenant of Middlesex, Lord Lieutenant of the County of London, and Lord Lieutenant of Huntingdonshire and the creation of the Lord Lieutenant of Greater London and of the Lord Lieutenant of Huntingdon and Peterborough.