4.—(1) These Regulations do not apply to the marketing of plant material intended for—
(a)trials or scientific purposes,
(b)selection work, or
(c)measures aimed at the conservation of genetic diversity,
if the plant material is marketed in accordance with an authorisation granted by an inspector.
(2) An authorisation—
(a)must be in writing;
(b)may be amended, suspended or revoked by notice; and
(c)may be subject to such conditions as the inspector considers necessary.