Mr Jenkin has quit partly in protest at the reorganisation which has hung over most of his 10 years in charge. He hopes schools will not suffer as a result of the changes, but he is not convinced.
"I don't approve of local government reorganisation. I think it's totally unnecessary. It's disruptive to education," he says.
Devon is one of the shires hardest hit by reorganisation. And while others talk of getting closer to schools, Mr Jenkin makes no bones. Has anything positive come out of it? "Nothing," he says.
In losing the newly-unitary Plymouth and Torbay, Devon has become an almost entirely rural authority - in the process losing the weighted funding that goes to urban areas. County town Exeter is now its only major centre. Combined with a Government settlement this year which favoured the cities, it amounts to a double whammy.
Devon is left with just 60 per cent of the population but 70 per cent of the schools, many of them village primaries which are more expensive to run. Disentangling the old county finances has left Devon pound;17 million short of a standstill budget. The council tax is up by 20 per cent.
"We've managed to protect virtually all of the schools budget but that's been at the expense of other services. We'll have no discretionary awards in Devon next year and we'll have significantly increased charges for post-16 and denominational transport," he said.
Like most reshaped shires, Devon has cut back on its central core, but it was already one of the lowest spenders on administration and management. Mr Jenkin says it's "considerably smaller than I would like". Advice and inspection are almost untouched, in keeping with Government priorities, but other support services such as personnel have been affected.
"I hope it will not mean a poorer service to schools. But it's very slim," he says.