Although Mr Clark received only half the pounds 6m he asked for, because he failed to win an additional pounds 3m claim for lost share options, the court awarded him the full benefit of his three-year rolling contract.
Normally executives receive much less than the full amount of their contracts, because the payoffs are negotiated downward when they depart.
The award stunned Rentokil Initial, which called it an "enormous sum" and announced it would appeal. It is four times the pounds 750,000 Rentokil Initial paid into court before the case, and three times the pounds 1m that Mr Clark said he offered to settle for, shortly after he was dismissed in April.
However, a Rentokil Initial spokesman said the company was astonished by the claim that Mr Clark had offered to settle for pounds 1m. "Our final offer was pounds 950,000 and we never received an offer to settle for pounds 1m."
Mr Clark, 55, said he had offered to have the matter referred to independent arbitration so that it could be dealt with quickly and privately to save pounds 600,000 legal costs, which Rentokil's shareholders will now have to pay.
He said he was now eager to continue his search for a "new challenge" as chief executive in a big organisation.
During the hearing, there were claims from Rentokil Initial's side that Mr Clarke had spent the summer playing golf and had not seriously looked for a job, and counter claims that it was unlikely that somebody his age could find another post as chief executive.
Mr Justice Timothy Walker rejected suggestions by BET that Mr Clark had not taken proper steps to mitigate his financial loss by seeking alternative employment.
The judge accepted evidence from a consultant who said he could recall only two instances when clients had accepted applicants over the age of 55.
The award was for loss of pounds 490,000 salary - including increases - during the three-year notice period to which he was entitled under his rolling contract, plus damages for loss of pension rights, bonus payments of 50 per cent of salary, an executive car and chauffeur, health insurance and the value of holiday entitlement.
Mr Clark was head-hunted by BET in 1991. He much improved the group's fortunes and there was no suggestion he was sacked for failure.Reuse content