Is it legally enforceable?

The guidance is non-statutory and is not binding on business. However, businesses should be aware that there might be reputational consequences if they do not follow the guidance; we have already seen in the context of taking advantage of furlough funding that not being in breach of the law is no protection against negative publicity. Further to the extent a contract expressly requires parties to act reasonably, it could be expected that this guidance is one of the factors a court would consider in determining what is reasonable.