Lieut. George Humphreys was nominated to the Coastguard on 18 April 1831 from the Coast Blockade Service, with a posting to Milton CGS (ADM 175/6 pdf 55).
If you believe he is your ancestor it would be worth ordering his Lieutenant's Passing Certificate from the National Archives, Cat.Ref: ADM 107/44 pages 193-194, which includes details of his birth, and ADM 6/110 page 104. He passed his Lieut's Board in 1812, but was not appointed until 1815.
Martin