(ii) Valuing Services
Where the claimant has provided a service which the defendant is unable subjectively to devalue, the objective value of the benefit will be adopted. Where the benefit takes the form of services it should follow that the defendant’s enrichment should be assessed as the reasonable value of those services by reference to the market. Determining the market value for services involves an assessment of the necessary costs incurred in doing the work,
plus a reasonable profit margin assessed by reference to the relevant industry rates and
In Cobbe v Yeoman’s Row Management Ltd233 the value of the claimant’s service in obtaining planning permission was valued as including his outgoings in applying for and obtaining planning permission, which was presumed to have been reasonably incurred unless the defendant could prove otherwise, and a fee for the service, which was to be assessed at the rate charged by an experienced property developer.
The reasonable profit margin will vary according to the circumstances, having regard to the margins which are typical in the industry, the nature and quality of the work, and the level of competition. So, for example, in MSM Consulting Ltd v United Republic of Tanzania234 a claim of ?250 per hour, for the provision of services involving the identification of property for the defendant to purchase, was considered to be too high since the claimant had no surveying or valuation qualifications. ?125 was considered to be a more appropriate rate for the particular claimant’s work.
Where the defendant is estopped from denying that he or she has been enriched, it follows that he or she is deemed to have received a benefit. Since no benefit will have actually been received, the measure of the enrichment should be assessed by reference to the market value of the claimant’s work.235 So, in a case such as Planche v Colburn,236 if the estoppel principle is adopted to identify an enrichment, the value of the defendant’s deemed benefit should be assessed by reference to the objective value of the claimant’s work in researching and preparing the manuscript.