25.—(1) Subject to paragraphs (2) and (3) the following conditions shall be complied with in the case of every vehicle—
(a)there shall be unobstructed access from every seat in the vehicle—
(i)in a case where the vehicle is, in accordance with the provisions of these Regulations, provided with only one exit, to that exit, and
(ii)in a case where the vehicle is, in accordance with those provisions, provided with two or more exits, to both or, as the case may be to at least two, of those exits;
(b)no seat in a vehicle shall be fitted to any door of the vehicle; and
(c)being a half-decked vehicle, there shall be no obstruction in the space between the floor in front of any passenger seat and the roof of the vehicle.
(2) Condition (a) of paragraph (1) shall not apply in relation to—
(a)any seat in a vehicle which is placed—
(i)beside the driver's seat if there is unobstructed access to that seat by means of an entrance other than the driver's entrance, or
(ii)on a deck which does not have a permanent top if there is unobstructed access from every seat on that deck to an exit; or
(b)an exit provided in accordance with the provisions of Regulation 21(11) unless such exit be a primary emergency exit or a secondary emergency exit.
(3) In the case of a double-decked vehicle as respects which provision is made for the placing of a barrier at the foot of the staircase leading to the upper deck, the vehicle shall not be treated as failing to comply with the requirements of the condition (a) of paragraph (1) by reason only that when that barrier is in position it would effectively prevent passengers from gaining access to the upper deck.