"It is no easy matter for an appellant to persuade a court to set aside a conviction based on a plea of guilty. There must be a strong case and exceptional circumstances: Nutall v R , unreported; CCA SCt of WA; Library No 920090; 26 February 1992; Pilkington v R [1955] TASStRp 11; [1955] Tas SR 144 and Harman v Ayling , unreported; SCt of WA (Parker J); Library No 960633; 5 November 1996. Before an appellate court will set aside a conviction of that kind, the appellant must show that there has been a miscarriage of justice: Duffield v R , unreported; CCA SCt of WA; Library No 950065; 14 February 1995 and Nobes v R , unreported; CCA SCt of WA; Library No 960486; 26 August 1996. In Harman, Parker J, at 5, after acknowledging that the circumstances which will amount to a miscarriage of justice can never be exhaustively identified, said that there are three well-recognised circumstances in which a plea of guilty will be set aside. The first is when the appellant did not understand the nature of the charge or did not intend to admit guilt; the second is if, upon the admitted facts, the appellant could not in law have been guilty of the offence; the third is where the guilty plea was obtained by improper inducement, fraud or intimidation and the like. See, in this respect, Meissner v R [1995] HCA 41; (1995) 184 CLR 132 at 157, per Dawson J, Maxwell v R [1996] HCA 46; (1996) 184 CLR 501 at 510 - 511, per Dawson and McHugh JJ, at 522, per Toohey J, and at 531, per Gaudron and Gummow JJ, and Tihanyi v R (1999) 21 WAR 377 at 390 - 391, per Murray J)."