17. The combined operation of s.56(1) and s.47 can be well illustrated by reference to s.56(1)(b). If a provision is incorporated in the Plan which is inconsistent with a particular development which was consented to, approved or authorized at the time when the provision took effect, the provision shall not prevent the carrying out or completion of the development, so long as the consent, approval or authorization was then current. The consequence is that the carrying out or completion of the development may be undertaken under s.47(3) without the consent of the planning authority, conditionally or unconditionally, as the case may be, depending on the nature of the consent, approval or authorization given before the relevant provision took effect. The operation which we have attributed to s.47(3) is unusual in the sense that it applies to both new developments (those not affected by s.56(1)(b)) and old developments (those affected by that paragraph). It is more usual to find an express provision dealing specifically with the right to carry out or complete a development authorized by or under earlier planning provisions. However, apart from s.56(1), the Act contains no provisions which could be classified as transitional in the sense already discussed. And the terms of s.47(3) are appropriate to the operation which we have accorded to the subsection. There is accordingly no need, so far as s.56(1)(b) is concerned, to take the drastic step suggested by the appellant of reading the opening words of s.56(1) as referring to "provision of the Act".