This paper reports new activities conducted as part of the JET technology programme under the WP-JET3 ACT sub-project collaboration. The aim of the sub-project is to take advantage of the significant 14 MeV neutron fluence expected during JET operations to irradiate samples of materials that will used in the manufacturing of main ITER tokamak components. Here, experimental measurements of dosimetry foil activity following irradiation in JET irradiation stations have been used as input to a neutron spectrometry unfolding methodology, which is based on an iterative non-linear least squares algorithm, to derive a new neutron spectrum. The new spectra are compared to those originally derived from simulations with the JET fission yield measurements as an input. Dosimetry foil activation measurements may be used as a complimentary fluence measurement system to that provided by integrated data from fission counter diagnostics, but with an additional benefit that useful spectrum information may be extracted, particularly above 2 MeV.