  Investigating, in direct continuation of our previous paper hep-ph/0606303
the implications of the non-unitarity of mixing matrices for non-degenerate
coupled systems that we demonstrated there, we examine more accurately the
vicinity of Cabibbo-like mixing in quantum field theory. We show that it is
possible to preserve one of its main features, namely that, in the space of
mass eigenstates, the two requirements -- of universality for weak diagonal
currents and -- of the absence of their non-diagonal counterparts, although not
fulfilled separately any more, can however reduce to a single condition for a
unique mixing angle theta\_c. This leads to tan (2 theta\_c)=+/- 1/2, or cos
theta\_c \approx 0.9732, only 7/10000 away from experimental results. No mass
ratio appears in the argumentation.
