1st April is the birthday of several English counties, and also the day on which several ceased to exist.
Today, for example, the county of Northamptonshire has vanished in a puff of administrative smoke. Yesterday it was a legitimate entity with a proper website and centuries of history but today it's been reborn as two distinct unitary authorities. It's all because the county council filed for bankruptcy in 2018, having sold off too many assets, over-outsourced services and failed to increase council tax. The government's solution was to split the county in two and start again.
The new councils are called West Northamptonshire and North Northamptonshire, and between them they replace seven former district/borough councils. To add to the nominative confusion West Northamptonshire includes the former district of South Northamptonshire and North Northamptonshire includes the former district of East Northamptonshire. The historic county of Northamptonshire remains for purely ceremonial reasons, and postal addresses won't change, but 'The Rose of the Shires' will no longer be administered as a whole.
Very few English counties have avoided some form of administrative reorganisation over the last few decades. Some have been split, merged or recombined, some have had populous metropolitan regions hived off and some have been summarily destroyed. The culprit is often a new unitary authority; the underlying rationale usually efficiency.
So here's my attempt to list those county changes, reverse-chronologically, ending up with the tiny handful I think have survived unscathed. Only the most recent significant adjustment is included. I haven't bothered with boundary changes.
1st April 2021
• Northamptonshire is split into West Northamptonshire UA and North Northamptonshire UA.
1st April 2020
• A single Buckinghamshire authority was created (minus Milton Keynes UA which left in 1997).
1st April 2019
• Bournemouth, Christchurch and Poole and Dorset UA was split off from the rest of Dorset.
1st April 2009
• Twelve years after losing Luton, Bedfordshire was divided into Bedford UA and Central Bedfordshire UA.
• Cheshire (which had already lost Warrington and Halton in 1998) became Cheshire West and Chester UA and Cheshire East UA.
• County Durham UA replaced seven lower tier authorities (having lost Darlington and Stockton-on-Tees in 1997 and Hartlepool in 1996).
• Northumberland UA replaced six lower tier authorities.
• Wiltshire UA replaced four lower tier authorities (Swindon having been severed in 1997).
1st April 1998
• Berkshire was carved up into six independent unitary authorities.
• Cambridgeshire divested itself of Peterborough UA.
• Devon lost City of Plymouth UA and Torbay UA.
• Essex removed Thurrock UA and Southend-on-Sea UA.
• Hereford and Worcester, merged in 1974, was separated back into Herefordshire and Worcestershire.
• Kent lost Medway UA (and Rochester lost city status).
• Nottinghamshire suddenly gained a hole (Nottingham UA).
• Telford and Wrekin UA withdrew from the rest of Shropshire.
1st April 1997
• Derbyshire lost Derby UA.
• Brighton and Hove UA withdrew from East Sussex.
• Portsmouth UA and Southampton UA separated from Hampshire.
• Leicestershire lost both Leicester UA and Rutland (which became a ceremonial county again).
• Stoke-on-Trent UA separated from Staffordshire.
1st April 1996
• The county of Avon reverted to the city/county of Bristol and three other unitary authorities, one originally part of Gloucestershire and two originally part of Somerset.
• The county of Cleveland broke up into Hartlepool UA, Middlesbrough UA, Redcar and Cleveland UA and Stockton-on-Tees UA.
• Most of these were incorporated into North Yorkshire, along with City of York UA.
• The county of Humberside vanished, reverting to the East Riding of Yorkshire, Kingston upon Hull UA and two unitary authorities formerly in Lincolnshire.
1st April 1965
• The creation of Greater London replaced London, eradicated Middlesex, absorbed significant chunks of Essex, Kent and Surrey and also swapped land with Hertfordshire.
Unchanged
• Cornwall (became a unitary authority in 2009)
• Norfolk (Norwich narrowly escaped going unitary in 2010)
• The Isle of Wight (since leaving Hampshire in 1890)
• The City of London (since medieval times)
Virtually all our English counties have changed, often significantly, in the last 60 years. We may not like it, but at least they do it on April Fool's Day to help lessen the blow.