Assensus Limiited v Wirsol Energy Limited

A contractual bonus entitlement must be identified from the parties’ agreement and its proper context. A general reference to a base salary does not imply an entitlement to an additional reasonable bonus where the agreement specifies particular bonus arrangements.

A term will be implied by fact only where it is necessary for business efficacy or so obvious as to go without saying. The existence of several possible remuneration arrangements, requiring further approval or negotiation, prevents implication. Where a subsisting contract governs the services and excludes a bonus, unjust enrichment cannot provide an alternative recovery.

Assensus claimed a bonus of £2,445,100 plus VAT from Wirsol for services provided on the Cleve Hill Solar Park. It relied principally on an alleged 2014 agreement providing £7,000 per megawatt upon planning consent. It advanced alternative claims for a reasonable contractual bonus, estoppel and unjust enrichment.

Assensus also claimed damages for termination without notice and statutory interest relating to a separate project bonus. The central issues were the scope and subsequent variation of the parties’ remuneration arrangements, whether any bonus term could be implied or supported by estoppel, and whether the ancillary claims succeeded.

1. The claims failed. The alleged £7,000 per megawatt entitlement did not apply to Cleve Hill. The 2014 arrangement concerned the 1.3 Renewable Obligation Certificate projects then contemplated, principally smaller subsidy-based solar sites. Cleve Hill was materially different in scale, nature and joint-venture structure.
2. The parties’ later remuneration arrangements superseded or varied the 2014 terms. The 2015 agreement introduced a different bonus regime applying to all projects. The 2016, 2018 and 2019 arrangements likewise showed that any Cleve Hill incentive remained to be negotiated and approved by senior directors.
3. No express term entitled Assensus to a reasonable bonus for projects outside the specified rates. The reference to a base salary did not establish such an entitlement.
4. The proposed implied term failed. The relevant inquiry was whether it was necessary for business efficacy or so obvious as to go without saying. The parties had used different bonus structures, discussed several possible forms of upside, and had not agreed either a trigger or amount for Cleve Hill. The contract remained workable without the proposed term.
5. The estoppel claim also failed. There was no unequivocally shared assumption that a reasonable bonus would automatically be payable, and Wirsol had not unconscionably resiled from any such assumption. An offer of £257,000 had been made and rejected.
6. Because the services remained within the scope of subsisting contractual arrangements, and those arrangements imposed no relevant bonus obligation, the claim in unjust enrichment was unavailable.
7. Alternatively, if a reasonable bonus had been payable, the appropriate figure would have been £157,500. The court preferred evidence based on market rates, historical remuneration, the project manager’s limited financial risk and the fact that Wirsol funded the project and specialist advisers.
8. The termination claim failed because three months’ remuneration had been paid and no further bonus would have arisen during the notice period. The Project Encore interest claim also failed: payment was conditional upon the amount payable by the third party becoming ascertainable or being received, and the parties had agreed an on-account payment without interest.