“10. A prayer for amendment of pleadings made after the commencement of a trial, shall ordinarily be declined. Where, however, the applicant establishes that despite the exercise of due diligence, he could not raise the pleadings sought to be pleaded by way of amendment, before the commencement of a trial, a court would be justified in allowing such an amendment. The power, therefore, to allow amendment of pleadings, even after the commencement of the trial, subsists, but with a caveat that the party praying for amendment must establish that despite the exercise of due diligence, the pleadings sought to be pleaded by way of an amendment could not be raised before the trial commenced. A court, therefore, may where it is of the opinion that the amendment is necessary for the purpose of determining the real controversy and if the applicant satisfies the court that despite the exercise of due diligence, he could not raise the pleadings before the trial commenced, allow such a prayer, even after the commencement of the trial.