My current car. If I remember correctly, I installed a simple inline toggle switch on Daphne when I owned her, and the feed wire was attached to the negative post on the original fuse "box." I never had a problem with that set up, but, as I said it CAN lead to problems. So on my latest DL, I bought a NOS clamp-on fused switch (that matched my heater switch) and ran a wire to the negative post on the main fuse "box."
BTW, the reasons I like adding a switch for the electric fuel pump are twofold: it allows you to use it to "prime" the carb in the winter, and starve the carb in case you flood it (although that's hard to do on a DL's updraft carb!). Also, it acts as another layer of theft-proof security if you turn it off when you park the car. A thief won't get far on only a float bowl full of gas!