19 All three parties, that is the plaintiff, defendant and Mr Oteri, knew that the defendant held a first mortgage G545917 over the Alness Street property, that it secured the repayment of $491,000, that Mr Oteri had purchased the Duncraig Road property and that the first defendant was to advance a further $40,000 to assist Mr Oteri pay the deposit on the Duncraig Road property. All three parties knew that Mr Pourzand had a second mortgage G647605 registered over the Alness Street property. All parties knew that Mr Oteri intended to sell, and did sell, the Alness Street property; they knew that as a result, when the Alness Street property was sold, both the defendant's first mortgage and the plaintiff's second mortgage were to be discharged, that a new first mortgage was to be taken by the defendant over the Duncraig Road property and that Mr Pourzand was to take a new second mortgage over the Duncraig Road property. All parties knew that as a condition of the $40,000 advance, the defendant required Mr Pourzand execute a deed of priority. All parties knew that the loan of $491,000 was to be "swapped", meaning that Mr Oteri would remain indebted for that amount as well as the extra $40,000 after the settlement regarding the Duncraig Road property. The deed of priority, when prepared, referred to the rule in Hopkinson v Rolt so all three parties can be taken to understand, in general terms at least, the effect of the rule.