Should estoppel be specifically pleaded

Querist :
Anonymous
(Querist) 14 June 2011
This query is : Resolved
Ld Counsels,
Plaitiff goes back on his admissions made in a registered document. Defendant denied any such fact that will make paintiff go back on his admission in the registered document.
However defendant did not specifically pleaded estoppel against plaintiff in his written statement but preferred an interim application raising the preliminary issue of estoppel.
Will the omission to plead estoppel by the defendant in his written statement disentitle or prohibit him in raising the issue estoppel in an interim application.
Kindly clarify. Thanks.