dardanelles counterstamped 1914 half crown

[yeniden11]

is there any recording about gallipoi campaign counterstamped half crown. i countered an 1914 half crown counterstamped 15 piastres. the characteristic of letters are same as on surcharged ten shillings and one pound banknotes. does it mean these coin stamped at treasury mint? is there any other example of this counterstamped coins? i could not find on myy search. what may be the price of this coin? following links are coin images: 

 https://d35fbhjemrkr2a.cloudfront.net/Images/Shop/46/Product/25938/1500/bf948c58d04c487f9600060863356093.jpg

https://d35fbhjemrkr2a.cloudfront.net/Images/Shop/46/Product/25938/1500/04a3ada0c2b3441c9767a293049f9cea.jpg

[Dafydd]

I've not seen anything like this previously apart from the usual counterstamps. Utterly fascinating. Thank you for sharing.

[Marsyas Mike]

I used to collect countermarked modern coins and these Arabic countermarks on silver coins are, from what I read, suspect.  This includes stuff listed in the Standard Catalog of World Coins, etc.  There is a lot of debate on these, but "spurious" comes up a lot.  But who knows?  I sure don't.  They are fun to look at. 

I like the OP, though I've never seen anything like it (and 20 years ago, I was researching this sort of countermark, not that a lot of information is out there).  There are a ton of "Arabic" countermarks on eBay that are clearly modern concoctions, so I'd be wary buying something like this.   Here are a couple I found on eBay with a basic "countermark" search - they look too good to be true to me:

Here's one I sold off a few years back - Djibouti countermarks, KM 3.2 per my 1996 catalogue.  This whole issue (usually found on Indian rupees) is questioned by a some  people.  My interests were shifting to ancients so I let it go.  It was nice to look at though: