  Realistic effective supergravity models have a variety of sources of lepton
flavour violation (LFV) which can drastically affect the predictions relative
to the scenarios usually considered in the literature based on minimal
supergravity and the supersymmetric see-saw mechanism. We catalogue the
additional sources of LFV which occur in realistic supergravity models
including the effect of D-terms arising from an Abelian U(1) family symmetry,
non-aligned trilinear contributions from scalar F-terms, as well as non-minimal
supergravity contributions and the effect of different Yukawa textures. In
order to quantify these effects, we investigate a string inspired effective
supergravity model arising from intersecting D-branes supplemented by an
additional U(1) family symmetry. In such theories the magnitude of the D-terms
is predicted, and we calculate the branching ratios for $\mu\to e\gamma$ and
$\tau \to \mu \gamma$ for different benchmark points designed to isolate the
different non-minimal contributions. We find that the D-term contributions are
generally dangerously large, but in certain cases such contributions can lead
to a dramatic suppression of LFV rates, for example by cancelling the effect of
the see-saw induced LFV in $\tau \to \mu \gamma$ models with lop-sided
textures. In the class of string models considered here we find the surprising
result that the D-terms can sometimes serve to restore universality in the
effective non-minimal supergravity theory.
