  We provide a formulation of generalised vector dominance (GVD) for low-x
deep-inelastic scattering that explicitly incorporates the ${\gamma}^{\ast} \to
q{\bar q}$ transition and a QCD-inspired ansatz for the $(q{\bar q})p$
forward-scattering amplitude. The destructive interference originally
introduced in off-diagonal GVD is recovered in the present formulation and
traced back to the generic structure of two-gluon-exchange as incorporated into
the notion of colour transparency. Asymptotically, the transverse
photoabsorption cross section behaves as (ln Q^2)/Q^2, implying a logarithmic
violation of scaling for F_2, while the longitudinal-to-transverse ratio
decreases as 1/ln Q^2.
