Persian Gulf. (Bahrain). 1951. Registered Air Mail envelope addressed to Bombay bearing Bahrain SG 54, 2a on 2d pale orange and SG 76, 4a on 4d light ultramarine (pair) tied by oval Registered/ Bahrain rubber date stamp in violet '15th Ap 51' with registered label and framed hand-struck 'Registered' on face and Bombay receiver. Very fine.