http://www.bailii.org/ew/cases/EWHC/Comm/2017/2909.html

As the textbook Russell on Arbitration explains, "The remission of an award does not deprive it of legal effect. It continues to operate so as to make the tribunal “functus officio”, unable to alter the award, on those matters which were not remitted". In this case, the arbitrator's jurisdiction was revived by virtue of a remission by the English court and an issue arose as to the extent of the revival of the arbitrator's jurisdiction. The defendant had made a claim for specific performance when it started the arbitration and had also indicated a claim for damages in lieu or, or in addition to, specific performance but had made no submissions as to quantum.

The judge said that "the arbitrator cannot, on the face of things, allow an amendment to enable a party to introduce a new dispute into the reference which has, by definition, ended at the time of the making of the Award.   The scope of the reference must be judged, in my judgment, as at the date of the initial award, since it is  only matters within that reference that jurisdiction can be revived in respect of.   However, in the final analysis, everything must depend on the proper construction of the Order of remission, viewed against the relevant background".

In this case, it was held that the remission did include a remission in respect of the damages claim and the arbitrator had jurisdiction to award further damages arising out of conduct which had taken place after the date of the award: "prima facie, a limited remission would be to deal with the matters before the arbitrator on the pleadings before him at the date of the original Award.   However, this can only be a prima facie rule, and, in an appropriate case  and, depending on the breadth of the order of remission, it may be that the arbitrator has to deal with matters that have occurred since the date of the First Award". Here, the remission incorporated the necessity to consider the damages claim, and that allowed the arbitrator to take into account matters occurring after the date of the award which led to an increase (or decrease) in the quantum of that claim.