Thanks very much, Freddy, I think we're getting somewhere!

However, to complicate matters even more, I've just been looking at the reports from three British naval vessels, all meeting at the same u-boat incident off Portland in May 1917. The first vessel, commanded by a regular naval officer, reports in GMT (and says so). The second vessel, commanded by a naval volunteer reserve officer, gives his times in BST (and says so). So, here we have two British vessels arriving at the same time with reporting times an hour apart. The third vessel, commanded by a regular naval officer, arrives five minutes later but doesn't specify which standard he is using, but his times agree with the BST officer!

It seems that the Admiralty might not have got around to insisting on only one time standard across the service - perhaps because BST had only been introduced the year before.

Chris Heal