By Henri Astier
BBC News, France
For more than two centuries French governments have sought to keep close tabs on opinion in a nation prone to revolutionary outbursts.
Informing ministers on public feeling - especially at election time - was long the responsibility of an outfit called the Renseignements Generaux (RG).
Ziad Khoury: We find out why people want to vote Yes or No
However, this shadowy police had its wings clipped after a wiretapping scandal in the mid-1990s.
Recently the government came up with an alternative system that is being tested for the first time in Sunday's referendum on a European constitution.
The job of monitoring local politics now falls to the prefects - the representatives of central government in France's 100 departments.
You might think that in these days of blogging and daily polls, the government does not need a small army of officials to take the pulse of public opinion.
But the head of the prefect's office in the western city on Nantes - and the man charged with gathering information on what locals are thinking ahead of the vote - says his work is crucial.
4 March: Voting date named14 April: Chirac TV debate28 April: Socialist ex-PM Lionel Jospin backs Yes in TV interview3 May: Chirac TV address16 May: Campaigns start
29 May: Referendum day
"An opinion poll will tell you whether people intend to vote Yes or No," Ziad Khoury explains.
"But you will not know if their choice is motivated by anger at the government's current policies, or whether they are judging the text (of the constitution) itself.
"So we provide a deeper level of analysis than you will have in a poll."
The prefects' reports give ministers a geographical breakdown of opinion trends, Mr Khoury adds.
"It is a useful complement" to polls, he says.
All the prefect's men
How exactly do Mr Khoury and his staff go about assessing opinion in the Loire Atlantique department?
In the past RG agents used to do a lot of footwork, talking to people in bars and attending country fairs.
Jean Mollet: A tobacconist who tries to steer clear of politics
These days the intelligence-gathering job carried out by the prefect's men tends to be office-based.
Year-in and year-out, they are expected to relay to Paris statements by local leaders and selected data on social trends.
A new system of panels has been pioneered ahead of the referendum. Mr Khoury and those under him are asking carefully chosen figures about what people around them are thinking.
Leaders of professional associations are being consulted openly (there is nothing underhand about it, Mr Khoury insists) during face-to-face meetings or over the phone.
"For instance representatives of tobacconists recently came to my office. These people see a lot of customers every day," says Mr Khoury.
"I took the opportunity to ask them how the issues at stake in the referendum were perceived and what trends they could observe. These are useful elements."
But how useful they really are, is debatable.
At least one tobacconist in Nantes denies that he has any insight into his customers' views.
"I always steer clear of politics," says Jean Mollet, who owns La Mayenne, a bar that doubles as a tobacco shop.
And patrons who do volunteer opinions cannot always be trusted, says Gerard Laine, a cafe-owner in the eastern city of Strasbourg.
"Sometimes they will voice left-wing opinions in a place run by someone who they believe is conservative, just to start an argument," he says.
Mr Khoury admits that his method is not foolproof.
The prefect system failed to predict the left's historic victory in last year's regional elections in the Pays de la Loire - previously a conservative stronghold.
"People say we got it wrong, but the polls also got it wrong," he says, hinting at frictions with his ministerial masters.
"The important thing is not to be right, but to assess how the country feels on a particular issue."
In Loire Atlantique, opinion on the proposed EU constitution appears to be as divided as in the rest of the country.
When asked to predict the verdict voters in his department will deliver, Mr Khoury only says: "Close."
More stories by Henri Astier on French opinion ahead of the referendum: