What relevance does the independent purpose and existence test have in common law?

In English jurisprudence, the only relevance of whether a transaction had a "genuine independent purpose and existence" was for determining whether its tax effects could be ignored. If a transaction had no other purpose than tax mitigation and was not intended to have an independent life, the courts could ignore the tax effect that the transaction otherwise would have had. This is the context in which the second and third parts of the Craven v. White test refer to independence. However, as discussed above, those parts of the test are not concerned with what transactions should be included in a common law series.