Unfortunately the makers mark is quite worn. Can you identify it anyway? I read it as "ETE". The 1. and 3. letter could also be "P", the 2. could also be a "F"... Maybe you see more. https://i.imgur.com/6O26L9U.jpg https://i.imgur.com/wWBaVrt.jpg https://i.imgur.com/9P7...
Do you think the use of the crown was limited to the Khedive's family? Or could it be EC for Evelyn Baring, 1st Earl of Cromer, who was the British controller-general in Egypt?