Difford's Guide remains free-to-use thanks to the support of the brands in blue above.
Mastiha (which after all is botanically flavoured spirit) combines wonderfully with gin and dry vermouth. A splash of ouzo adds more Greek interest.
Created by yours truly (Simon Difford) in August 2015 at the Cabinet Room, London, England. (If only I were on a Greek island.)
Our Martini cocktail page details its evolution and other common variants.