32 In the present circumstances, I am, however, of the view that the arrangements between the parties with respect to the payments relied upon by Landmark are not properly characterised as mere indulgences by a vendor to a purchaser, of the kind one might see commonly in conveyancing transactions or otherwise. In each case, the correspondence between the solicitors for the parties evidences promises by both Landmark and Monash as part of the "revised" arrangements. From the perspective of the law of contract, I am of the view that it is clear that in each case, the vendor's agreement to extend the settlement date is met by an agreement to pay early part of the purchase price and interest. In other words, no gratuitous promises are involved, there is consideration, a promise for a promise. Absent mere gratuitous promises, having found consideration, the fact that in the circumstances of Australian Horizons[20] and Ottedin Investments[21] the contractual variations were made, formally, by deed of variation does not detract from the contractual effect of the variations in the present circumstances.[22] Although the absence of consideration in an agreement under seal may affect the availability of relief by way of specific performance, that issue does not arise here. For these reasons, I accept Landmark's submissions that the contract of sale was varied to provide for the payments to which reference has been made. The result was that the terms of the varied contract of sale required and obliged Monash, as vendor, to accept settlement at the later agreed date and obliged Monash, as purchaser, to make the part payments of the purchase price and interest as agreed.