"79. ... the proposition is that proceedings can be commenced only in respect of an existing cause of action and that judgment cannot, therefore, be given in respect of monies which have only fallen due subsequent to the commencement of proceedings. 80. In the case of a cause of action for damages, it seems to me that the proposition is plainly wrong. Provided that the cause of action conferring the right to damages is complete at the time when the action is commenced, damages will be assessed as at the date of judgment. 81. But the same does not generally hold true in relation to claims for a liquidated sum. In such cases, the almost invariable rule appears to be that the amount must be ascertained or ascertainable as at the date of commencement of proceedings. Thus, for example, a landlord's claim for rent must be quantified as at the date of commencement of proceedings, notwithstanding that further rent may continue to fall due in the period prior to judgment. The same would apply to claims on a hire purchase agreement, though commonly, in such cases, the agreement will have been determined and future instalments may, accordingly, be indirectly recovered by way of a claim for damages. 82. The distinction between a claim for a debt and for damages is deeply entrenched in the law. Its origins are, no doubt, to be found in the old forms of action which, as Maitland observed, 'still rule us from their graves'. 83. But, whatever the origins of the distinction, there appear to be few if any exceptions to the principle that a debt must be ascertained or ascertainable as at the date upon which the proceedings are commenced. Whilst mesne profits in a possession action may be computed up to the date upon which possession is given, they represent tortious damages rather than a debt. So the only real exception to which my attention was drawn seems to be the current practice by which interest pursuant to contract can be claimed against the contracting party, right up to the date of judgment in an action to recover the principal debt."
"The overriding objective is that the court should deal with cases justly. That includes, so far as practicable, ensuring that each case is dealt with not only expeditiously but also fairly. Amendments in general ought to be allowed so that the real dispute between the parties can be adjudicated upon provided that any prejudice to the other party or parties caused by the amendment can be compensated for in costs, and the public interest in the efficient administration of justice is not significantly harmed."