Yarrow is a lovely delicate flavour, which matches really well with the subtle elderflower.   It is a delightful soft drink, or try with a floral gin, say Bloom, Daffy's or Sir Robin Locksley.  With Gordon's Pink Gin it is a revelation, and with Pinkster Hedgepig it is unbelievable.  Turns a dry prosecco into something much more interesting!
Amazing value for handcrafted products like these.