The original Blinker from Patrick Gavin Duffy's 1934 The Official Mixer's Manual uses grenadine but the folk at Hawksmoor have switched this for a few...
Yes, I think muddling the raspberries is the only way you're going to get much of their flavour into the cocktail. I can't recall a shaken drink that calls for berries without muddling them first. I made this the other night using a raspberry syrup (was OKAY), which is a better option if you have it available.