I wrote to Ilford some weeks ago about led illumination and use of multigrade ilford filters and this is the answer:
"First the good news! I believe that the ban on tungsten bulbs in Europe only extends to domestic bulbs. Equipment and specialist lamps are not included - yet. If you are using the Multigrade filters I would recommend using tungsten light as the filters were designed using the "black body-ish" wavelength range of tungsten. LED outputs are always going to be spiky! Filters and white LED will work to some extent but the 1/2 grade spacings may be compromised in interesting and challenging ways and I would expect a reduced contrast range (potentially similar as for people who have tried to use fluorescents and MG filters). The degree of difference will depend on the output of the LED used. It is possible that a particular LED will be such a good match that it works almost as well as tungsten. This would only be found by trying it. Also, your english seems excellent. Please reply to this email with any further questions."
What do you think?