‘The claimants point out that the valuation evidence can never relate precisely to the date of the award since the tribunal’s rules require that its decision shall be given in writing and the award is consequently and necessarily in the nature of a reserved judgment. We think there is nothing in this. The award must be based on evidence; the evidence must be given at the hearing and so to some extent must antedate the award but normally the interval will be short and of no significance. If in a particular case the tribunal were to think it likely that the values had changed materially since the hearing and before the award was promulgated, further evidence could be heard and, if though desirable, arrangements could be made for the award to follow almost immediately after the further hearing.’