Why ought a third-party promisee to a contract make his claim in the alternative?

Question

Paul Davies. JC Smith's The Law of Contract (2018 2 ed). p. 135.

1. How's the red underline true? How's "third parties" ambiguous? The textbook refers to the Introduction that doesn't define "third parties", but Section 1 does:

(1) Subject to the provisions of this Act, a person who is not a party to a contract (a “third party”) may in his own right enforce a term of the contract if—

2. I don't understand why "C, when he is a promisee, would be well advised to make his claim in the alternative." Wouldn't judges follow the Law Commission's standpoint as I underlined in purple? Davies doesn't expatiate why courts wouldn't?

Answer 1

1. It's ambiguous because it is not clear if a person named in a contract (as benefiting from it) is a party to that contract or not. For example, a named beneficiary in a life insurance policy is not a party to the contract and can benefit from the Act. However, a child in a private school where the contract is between the school and the parent could be argued to be a party to that contract (or not). It's not that the definition is ambiguous - it's that the application to particular facts is problematic. However, as the Act is 17 years old at the time the textbook was published it seems odd that there is no case law clarifying the issue - maybe it never has been an issue?

2. Because courts don't apply the law as a whole - they apply the law to the dispute brought by the parties.

   If a plaintiff were to bring a case only under the Act and the court finds the Act doesn't apply to them then that's it - game over. However, if they bring a case under the Act and "in the alternative" at common law then if they fail to engage the jurisdiction of the Act the case would then be decided at common law. In addition, the author is casting doubt that the precedent would be applicable - i.e. the Law Commission might be wrong.