Premise: RAF Mount Batten was a Royal Air Force station and flying boat base at Mount Batten, a peninsula in Plymouth Sound, Devon, England. Originally a seaplane station opened in 1917 as a Royal Navy Air Service Station Cattewater it became RAF Cattewater in 1918 and in 1928 was renamed RAF Mount Batten. The station motto was "In Honour Bound" which is the motto of the Mountbatten family.
Hypothesis: RAF Mount  was opened in the 20th century.