Further to the thread i started last week i have the official answer from Winchester firearms department-
rifled muzzleloaders are section 1,
smoothbore muzzleloaders are section 2, and most importantly-
solid shot is fine to use in a smooth bore muzzle loader on a section 2 shotgun licence!!
also there is no legal distiction between conventional spherical ball ammunition and conical rifled slugs..
im a happy chappy..