In this talk, we discuss a simplified version of a recently proposed
twin Pati-Salam (PS) theory of flavour broken to the $G_{4321}$ gauge group at high energies, then to the Standard Model at low energies,
yielding a TeV scale vector leptoquark $U^{\mu}_1(3,1,2/3)$ which may be used to address the
lepton universality anomalies $R_{K^{(*)}}$ and $R_{D^{(*)}}$ in $B$ decays.
The model also accounts for quark and lepton mass hierarchies, providing a link between the flavour anomalies and a theory of flavour.