folded letter datelined "Liverpool April 30th 1852", endorsed "Consignees p Great Britain Steamer", did not enter the British postal system but was placed on Great Britain departing Liverpool May 1 and arriving New York May 14, New York circled "6" ship rate handstamp and straightline "2nd Delivery", very fine, the only recorded cover carried by Great Britain after her 1846 grounding and an uncommon non-contract steamship sailing