Paragraph 6
Within 24 hours of any burial in a walled grave or vault, the coffin shall be—
(a)
embedded in concrete, and covered with a layer of concrete not less than six inches thick; or
(b)
enclosed in a separate cell or compartment of brick, slate, stone flagging or precast concrete slabs of a 1:2:4 mix, in any case not less than two inches thick, in such a manner as to prevent, as far as may be practicable, the escape of any noxious gas from the interior of the cell or compartment.