Lepton Flavour Universality tests in $B$ decays as a probe for New Physics

In the Standard Model (SM), the coupling of the electroweak gauge bosons to the leptons is lepton flavour universal. Tests of this property constitute sensitive probes for new physics models that violate lepton flavour universality. Recent tests of lepton universality in rare $b\to s\mathrm{\ell }\mathrm{\ell }$ decays and semileptonic $b\to c\tau {\bar{\nu }}_{\tau }$ transitions have shown some tensions with the precise SM predictions. These proceedings summarise the latest results on lepton flavour universality from the LHCb experiment.