Simon, I revisited this drink again over the weekend with the addition of creme de menthe and I have to say I think I preferred the version in the book that I have but obviously everyone will be entitled to their own tastes! Thanks for the your response on my previous message.
The online version of this drink calls for 4 drops peppermint bitters while the printed 16th Edition Difford's Guide specifies 4 dashes. Which is it - dashes or drops? Thanks.
Should be drops if using strong bitters such as Bob's Mint Bitters but could be dashes if another brand such as Fee's. (sorry it took me so long to come across and answer your comment.)