Section 224 (Enforcement of control as to advertisements) of the Town and Country Planning Act 1990 (c. 8) shall apply in the area of a borough council as if—
(a)in subsection (5) for the words “if he proves that it was displayed without his knowledge or consent” there were substituted “if he proves either of the matters specified in subsection (6) below”; and
(b)after that subsection there were inserted—
“(6)The matters are—
(a)that the advertisement was displayed or, as the case may be, continued to be displayed without his knowledge; or
(b)that he took all reasonable steps and exercised all due diligence to prevent the display or, as the case may be, to secure that the display was discontinued.”.