I'm a little confused as to how the adjective is structured here. If you were saying simply "our worker" you would say "ο εργάτη μας". So why does the μας now go between the adjective and the noun? Can a Greek speaker explain the grammatical principle at work here?
There are two ways of adding a possessive pronoun to a noun when an adjective is also present. Both Ο βασικός εργάτης μας and Ο βασικός μας εργάτης are correct. The second phrase places a little more emphasis on βασικός, as if you're making a distinction between your main and another type of worker: Ο βασικός μας εργάτης είναι ο Γιώργος αλλά ο πιο παλιός είναι ο Γιάννης. - Our main worker is George but the oldest is John. You could still say Ο βασικός εργάτης μας είναι ο Γιώργος αλλά ο πιο παλιός είναι ο Γιάννης and it'd be just as fine. It really is a minor thing and it is mostly in spoken Greek that this kind of emphasis becomes more pronounced with intonation.
thanks for the clear and thorough explanation. it will be a while before I can know how to follow your advice but hopefully someday i'll get there ;)