"…Benefit, therefore, cannot be the test. There must be a real connection, a nexus, between the expenditure and the business. It seems to me that the nexus, if it is not to be benefit, must be directly referable to the purpose of the business. By the purpose of the business in this context, I mean by reference to an analysis of what the business is in fact doing. It is only by identifying what the nature of the business is in that way that one can determine the extend to which any given expenditure can be said to be for the purposes of that business."