Mistake is another vitiating factor and it has be operative in order to render a contract void or voidable At common law it will render the contract void ab initio and nullify any property passed or obligations created.Mistake at equity may make the contract voidable for mistake which means that the contract has an option of being avoided and will be The law relating to mistake is not statutory and can be inferred from a number of case law.It has often been stated that the categorization of the types of mistake etc is confusing and should be reformed.The effect of mistake is that if the contract is void at law then the there is no remedy of specific performance available either.(Nutt v Read (1999) The Times, December 3.)
Consideration is an integral part of a contract essentially what really makes an agreement a fully enforceable contract.It has been defined in many case law authorities such as the statement of Lush J. in Currie v Misa (1875) LR 10 Exch 153: " some right, interest, profit or benefit accruing to one party, or some forebearance, detriment, loss or responsibility given, suffered or undertaken by the other."Another has been given by Frederick Pollock, approved by Lord Dunedin in Dunlop v Selfridge Ltd  AC 847, is as follows:"An act or forebearance of one party, or the promise thereof, is the price for which the promise of the other is bought, and the promise thus given for value is enforceable."
Consideration is called "executory" where there is an exchange of promises to perform acts in the future and if one party makes a promise in exchange for an act by the other party, when that act is completed, it is executed consideration.The court will however not inquire into the quantity or value of consideration here (Chappell & Co Ltd v Nestle Co Ltd  2 All ER 701.).Secondly the law as it stands requires that the consideration must move from the promisee or that it was provided for him.Finally it does not have to move to the promisor.(Price v Easton (1833) 4 B & Ad 433).
Gibson, A & Fraser, D 2007, Business Law, 3rd edition, Pearson Education, Australia
D.G.Cracknell(2001)Obligations; Contract Law ,Old Bailey