What can we learn from this case?
If the subject to contract tag is positioned on the front of the document, it usually is taken to include all terms within the document, unless specified otherwise.
In order for such a document to be legally binding, all parties must sign the document. In the case of Farrar v Rylatt, there was no claim to the profit generated by the joint venture as detailed in the Heads of Terms agreement as the joint venture clause was not highlighted as being exempt from the subject to contract tag and because the document was not signed by all parties.
It is important to always ensure that the final contract you want to agree encapsulates all of the terms required, that any terms you want included or excluded from the subject to contract tag are identified specifically and that the document is signed by all parties to ensure it is legally binding.