An announcement of the Ministry of Foreign Affairs of Siam dated 22 February 1927 on application of the expedition treaty between Siam and Britain dated 4 March 1911 <a href="https://en.wikipedia.org/wiki/Common_Era" class="extiw" title="w:Common Era">CE</a> to territories subject to Britain, as published in the Siamese Government Gazette on 26 February 1927.
Government of Siam
1927-02-26
<a rel="nofollow" class="external text" href="http://www.ratchakitcha.soc.go.th/DATA/PDF/2470/A/334.PDF">Royal Siamese Government Gazette, volume 44, part 0 A, page 334, dated 26 February 1927</a>