I am having building work done. The builder says he is newly registered so his siret number is "en cours" [being processed]. Can I still check his registration somewhere - how long can a siret be en cours? G.F.

The siret is a 14-figure number identifying a business, issued by national statistics body Insee. You will also hear references to siren numbers, which is actually the first 10 figures of the siret.

An Insee spokeswoman said that siret numbers were usually issued in a matter of a few days from them receiving the request and businesses should not be operating without one.

She said you should therefore be wary of such a firm.