The photon wave equation proposed in terms of the Riemann–Silberstein vector is derived from a first-order Dirac/Weyl-type action principle. It is symmetric w.r.t. duality transformations, but the associated Noether quantity vanishes. Replacing the fields by potentials and using instead a quadratic Klein–Gordon-type Lagrangian allows us to recover the double-Chern–Simons expression of conserved helicity and is shown to be equivalent to recently proposed alternative frameworks. Applied to the potential-modified theory the Dirac/Weyl-type approach yields again zero conserved charge, whereas the Klein–Gordon-type approach applied to the original setting yields Lipkin's “zilch”.