A 14MeV neutron spectrometer, based on the principle of the proton recoil telescope, has been installed as a DT plasma diagnostic at JET. The device comprises three identical telescope modules arranged one behind the other, to increase efficiency without worsening resolution. It views the plasma along a horizontal line of sight. The total efficiency is 7.05x10-5 counts per [neutron per cm2], and the calculated response function has a FWHM of 2.2% at an incident neutron energy of 14.1MeV. The spectrometer was operational throughout the recent Deuterium-Tritium Experiment No.1, and selected neutron spectra have been analysed in terms of the contributions from the various neutron production mechanisms.