  A systematic approach is followed in order to identify realistic D-brane
models at toric del Pezzo singularities. Requiring quark and lepton spectrum
and Yukawas from D3 branes and massless hypercharge, we are led to Pati-Salam
extensions of the Standard Model. Hierarchies of masses, flavour mixings and
control of couplings select higher order del Pezzo singularities, minimising
the Higgs sector prefers toric del Pezzos with dP3 providing the most
successful compromise. Then a supersymmetric local string model is presented
with the following properties at low energies: (i) the MSSM spectrum plus a
local B-L gauge field or additional Higgs fields depending on the breaking
pattern, (ii) a realistic hierarchy of quark and lepton masses and (iii)
realistic flavour mixing between quark and lepton families with computable CKM
and PMNS matrices, and CP violation consistent with observations. In this
construction, kinetic terms are diagonal and under calculational control
suppressing standard FCNC contributions. Proton decay operators of dimension 4,
5, 6 are suppressed, and gauge couplings can unify depending on the breaking
scales from string scales at energies in the range 10^{12}-10^{16} GeV,
consistent with TeV soft-masses from moduli mediated supersymmetry breaking.
The GUT scale model corresponds to D3 branes at dP3 with two copies of the
Pati-Salam gauge symmetry SU(4)\timesSU(2)R\timesSU(2)L. D-brane instantons
generate a non-vanishing mu-term. Right handed sneutrinos can break the B-L
symmetry and induce a see-saw mechanism of neutrino masses and R-parity
violating operators with observable low-energy implications.
