Steve Sharp, Buckinghamshire's chief education officer, is stepping down as the county faces up to the consequences of local government reorganisation.
With Milton Keynes set to become a unitary authority from next April, serious "downsizing" is taking place in the country's one Tory-controlled shire.
Thirteen departments are being replaced by four new super-directorates central services, environmental services, social services and education which will include libraries, museums and county archives.
All chief officers have been asked whether they prefer to stay or go and Mr Sharp, 50, who has been at Shire Hall for 12 years, is one of five who will be leaving, probably in the autumn.
"The county won't be the same without Milton Keynes," he said. "Part of what brought me to Bucks was the diversity of the old county and new county and things are going to be very different."
Mr Sharp, a former chair of the county education officers society, opposed the break-up of Buckinghamshire.
He argued that : "Reorganisation of local government in Buckinghamshire, excluding Milton Keynes, would be a massive gamble."
The county is expecting major cuts in its budget. The loss of Milton Keynes means it will cease to be responsible for services for a third of its population, accompanied by a reduction in budget of about 36 per cent.
On top of that, Mr Sharp said the local authority was preparing for a low financial settlement from Government. "Chancellor Kenneth Clarke has promised us one."
Mr Sharp joined Buckinghamshire in 1988 as its deputy education officer, becoming chief four years later.
Nationally, he has been chairman of the primary education study group and a member of the Audit Commission advisory group on under-fives.
"The things that stand out about the job are the fun of working with committed people in the education service, whether they are heads, governors, teachers or people working in the youth service. That is what I am going to miss."