I own what seems to be a Lieutenant/Officer's bicorn from Gieves Ltd. I'm not sure about its date, but it should be at least from 1918 when Gieves moved to 21 Old Bond Street. It's a size 4/55cm which I find rare because it's a small size, so I assume it belonged to a very young officer. It's in pretty good condition, though it has 2 details. The bullion on top is loose and the button was missing. Luckily, I had an original one from Gaunt maker to go with it. I'm trying to restore it but I don't have information on how the button should be sewn. It looks like it should be sewn with a long thread to reach the bicorn's surface, but I'm not sure. I will appreciate any help on the subject.