Here's a more clearer photo from the book: "Pilot Cutters Under Sail: Pilots and Pilotage in Britain and Northern Europe" by Tom Cunliffe (Pilot Cutters Under Sail: Pilots and Pilotage in Britain and Northern Europe: Amazon.co.uk: Tom Cunliffe: 9781848321540: Books)
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Great! There you can see what I have try to show, the sail is different in 1912 having "No 1" on top and "I W" below it.
That book is still on my to buy list for 3 years now. Maybe I should buy it soon!