The Lithium Beam Probe (LBP) is widely used for measurements of the electron density in the edge plasma of magnetically confined fusion experiments. The quality of LBP data strongly depends on the stability and profile shape of the beam. The main beam parameters are: beam energy, beam intensity, beam profile, beam divergence and the neutralization efficiency. For improved monitoring of the beam parameters, a Beam Profile Monitor (BPM) from the National Electrostatic Corporation (NEC) has been installed in the Li beam line at JET. In the NEC BPM, a single grounded wire, formed into a 45o segment of a helix, is rotated by a motor about the axis of the helix. During each full revolution, the wire sweeps twice across the beam to give X and Y profiles. In this paper we will describe the properties of the JET Li beam as measured with the BPM and demonstrate that it facilitates rapid optimization of the gun performance