What was the ratio decidendi crabtree-vickers pty ltd v australian direct mail advertising and addressing co 1975 hca 75?

In Crabtree-Vickers Pty Ltd v Australian Direct Mail Advertising and Addressing Co 1975 HCA 75, the High Court of Australia held that the doctrine of privity of contract (the legal principle that a contract can be enforced only by a party to it) did not apply to a contract of indemnity between two parties. The Court held that the doctrine of privity did not apply because the indemnity contract was not a contract for the benefit of the third party, but rather was a collateral contract that was independent of the main contract between the two parties.