First measurements and identification of Minority Ion Cyclotron Emission (MICE) during ICRF (H)D minority heating in the JET tokamak are presented. An inner wall radiofrequency (rf) probe shows the new single MICE spectral line, downshifted from the heating frequency and appearing ~ 400 ms after the ICRH switch-on. The line is narrow (Δω/ω≈0.04), characterised by the ion cyclotron frequency of minority protons in the outer edge mid-plane plasma and is observed irrespective of whether single or multi-frequency ICRH is applied. Threshold conditions for MICE are: coupled RF power to the plasma Prf ≥ 4.5MW; total fast ion energy content Wfast ≥ 0.6MJ. At the time of the rapid switch-on of MICE, the measured power loss from the energetic minority ions is ≈0.1±0.1MW, consituting <2% of Prf. The observations are consistent with the classical evolution and population of the plasma edge with ~3MeV ICRH protons on orbits near the outboard limiters. Particle loss and energy filtering contribute to a local non-Maxwellian energetic ion distribution which is susceptible to ion cyclotron instability.