Let's just say I've had quite a bit of experience as my tavern was known for serving "proper cocktails".
Without exception Bombay Sapphire is the cleanest tasting Gin.
Thus a proper gin Martini:
7 parts Bombay Sapphire, 1 parts Dolin Dry vermouth, mixed well with plenty of ice and served "up" in a chilled Martini glass.
Garnish with the yellow, none of the white, lemon rind only for a true taste of a classic Martini served classically
Be careful as it's going to taste like "more" ;-) You can always add an olive of your choice only if you insist :-(