Made this with plain gin (Plymouth) - and according as the 2020 printed Difford's Guide recipe - very acceptable, truly "flowery" with orange, lime and grenadine combining in a pleasing way. I give this 4 stars.
Tried it both ways. One as posted above ( 1 1/2 oz Plymouth) and second as recommended below (2 oz Plymouth). I prefer the 1 1/2 oz. When the Plymouth is increased, it becomes the dominant flavor (not a bad thing ) and any hint of orange flavor is lost.