THAT hugely productive correspondent of this newspaper Richard Woodman is progressing well with his five volume history of the British merchant navy, the first of which was reviewed earlier this year in this column. He tells me that while most of us are on the beach or sheltering from the rain, he is sweating over the final volume. After Neptune’s Trident, Britannia’s Realm is the second volume to be published, taking the reader from 1763 to 1815, and a period in which this nation lost one overseas empire and gained another, while being almost continually at war.