Thanks for the prompt replies.
The lamps are dichroic.
I fitted the hoods following a visit to another electrical trade outlet who said I needed to fit them !!!
I have had four LV shower lights fitted to my 2 metre sq bathroom (IP65 rated). Before the electrician did the job I re-panelled the ceiling with purpose designed plastic panelling and fitted the lights into this and subsequently into the loft.
I have also fitted insulation fire retardant...