I have a massive collection of coins that my Dad collected. I have identified most of them but not this coin. I have 3 of these exact coins.
Thanks to our fb friend Johnny, this is a transportation token used on the famous Galata Bridge in Instabul. Here is a nice one:
It sold for $8 US dollars on eBay. Yours would be worth about $3 due to condition.
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Thank you very much, that's fascinating! It must have been kept by my grandfather from his time in the King's Dragoon Guards.