Let \(\Omega \subset {\mathbb {C}}^2\) be a smooth domain. We establish conditions under which a weakly conformal, branched \(\Omega \) -free boundary Hamiltonian stationary Lagrangian immersion u of a disc in \({\mathbb {C}}^2\) is a \(\Omega \) -free boundary minimal immersion. We deduce that if \(u\) is a weakly conformal, branched \(B_1(0)\) -free boundary Hamiltonian stationary Lagrangian immersion of a disc with Legendrian boundary, then \(u(D^2)\) is a Lagrangian equatorial plane disc. Furthermore, we present examples of \(\Omega \) -free boundary Hamiltonian stationary discs, demonstrating the optimality of our assumptions.