Nauru 17 to 27a paying the postage plus the registration fee to England.  This is the lower values of the set complete  on 2 registered covers sent to England.  The covers have consecutive registration numbers.  The covers appear to be cancelled 3 MY 4.  I must assume this is 1947 as the 3 pence was not issued until then.  A great and rare piece of Nauru postal history.  As used stamps the stamps have a scott catalogue value of well over $100.00.  Legitimately used on a registered cover showing actual p[ostage useage the covers should be worth that and more.