A footing may—
(a) support a party wall; and
(b) extend beyond the boundaries of a street alignment—
(i) to a distance of not more than 300mm if the highest projecting part of the footing is at a depth of not less than 450mm but less than 3m below the ground level; or
(ii) to a distance of not more than 1m where the highest projecting part of the footing is at a depth of 3m or more below the ground level.