The declarations signed Sign_agreement by the Sultans of Muscat to consult Communication the British government on all important matters , the unequal trade treaties signed Sign_agreement by the two sides favoring British interests , the cessation of the Omani Kuria Muria islands to the British , and the vast control Control over the Sultanate 's government ministries , including defense and foreign affairs , exerted by the British rendered Supply the Sultanate a `` de facto '' British colony .