“[11]. … to ascertain ‘such a sum of money as might reasonably have been demanded by [the claimant] from [the defendant] as a quid pro quo for [permitting the breach of covenant to perpetuate]’, to use (and adapt) the formulation of Brightman J. in Wrotham Park v. Parkside Homes [1974] 1 W.L.R. 798 at 815D. This basis of assessing damages was approved in Jaggard v. Sawyer [1995] 1 W.L.R. 269, and explained further in Attorney-General v. Blake [2000] 3 W.L.R. 625. 12. It is also common ground that the way of ascertaining what that sum is, is to consider the sum that would have been arrived at in negotiations between the parties had each been making reasonable use of their respective bargaining positions without holding out for unreasonable amounts. This requires, in turn, that the parties have regard to the cost or detriment to the claimant and the benefits for the defendant of the latter's being allowed to [breach the covenant]. …. 13. The negotiation analysis is not pursued rigorously to its logical end. I do not have to imagine a negotiation in which the parties have to guess at something which events have in fact made certain. In carrying out my exercise, I can take into account the actual events that have happened, and the actual benefits accrued, as at the date of the trial. In Wrotham Park, Brightman J. held that the starting point for the calculation would have been the plaintiff asking "the developer what profit he expected to make from his operations. With the benefit of foresight [sic] the developer would, in the present case, have said about£50,000 , for that is the profit which Parkside concedes it made from the development" (at p. 815H). What Brightman J. seems to have been doing there is to imagine a negotiation before the infringement, but using actual profits as evidence of what the parties would have contemplated at the time (before they actually accrued). In A.-G. v Blake, Lord Nicholls expressed himself a little differently when he said (at p. 637H): "In a suitable case damages for breach of contract may be measured by the benefit gained by the wrongdoer from the breach. The defendant must make a reasonable payment in respect of the benefit he has gained." He seems to have treated Wrotham Park as an example of that; indeed, he described it as "a solitary beacon". While he does not use the concept of a hypothetical negotiation, I think that Lord Nicholls is in effect saying the same thing as Brightman J. While an imaginary negotiation is not necessarily the appropriate supposition in all cases (and not in Blake itself) I think that it is helpful. I therefore propose to consider this case on the basis of what the evidence shows about the level of gain to [the defendant] and what a reasonable negotiation would have produced based on that evidence.”