FREE MOVEMENT OF PERSONS - WORKERS - DEROGATIONS - RESTRICTIVE INTERPRETATION - ACT OF ACCESSION OF THE HELLENIC REPUBLIC - TRANSITIONAL PROVISIONS - WORK PERMIT - FIRST GRANT TO A GREEK NATIONAL - CONDITIONS - STRENGTHENING OF NATIONAL RESTRICTIONS AFTER THE ENTRY INTO FORCE OF THE ACT OF ACCESSION - PROHIBITED ( EEC TREATY , ART . 48 ; ACT OF ACCESSION , ARTS 44 AND 45 ( 1 ))