2(1)A vehicle is an excepted vehicle if it is—
(a)an agricultural tractor, or
(b)an off-road tractor.
(2)In sub-paragraph (1) above “agricultural tractor” means a tractor used on public roads solely for purposes relating to agriculture, horticulture, forestry or activities falling within sub-paragraph (3) below.
(3)The activities falling within this sub-paragraph are—
(a)cutting verges bordering public roads;
(b)cutting hedges or trees bordering public roads or bordering verges which border public roads.
(4)In sub-paragraph (1) above “off-road tractor” means a tractor which is not an agricultural tractor (within the meaning given by sub-paragraph (2) above) and which is—
(a)designed and constructed primarily for use otherwise than on roads, and
(b)incapable by reason of its construction of exceeding a speed of twenty-five miles per hour on the level under its own power.