Thanks everyone.
The site is VERY High Profile, very large and has 24 hour security. I have extensive experience of shooting Canada Geese but have never had to consider NIGHT shooting them, and a cursory comment from someone suggested that was illegal, I didn't think it was, but because of the nature of this site I must be absolutely 100% sure.
General Licences inc.CL12, FAC Conditions, Other means of removing them have been tried, Lighting, rifles, shotguns, ammo types, Sundays, Bank Holidays, Geese numbers, specific location on site, number of operatives, safety, neighbours etc