Thank you all monks for your help. I think that , thanks to you, I have found a full DateTime solution :

    my $Date3= $Date->clone()->set_time_zone('floating')->set_time_zon
+e( 'UTC'    )->set_time_zone( 'Europe/Paris'    );
[download]

That is, remove Paris time zone code, by converting to floating, set UTC time code, then convert by setting Paris time code.