ChD 11 July 1986. A dispute between the plaintiff landlords and the defendant tenants on the amount of service charge payable under the leases for flats . The leases were each for a period of 61 years from June 1960. They stipulated that the service charge should be £100 per annum plus £1 per annum for each point or part of a point by which the Retail Price Index rose above 110.4. There was a proviso that if the RPI ceased publication or was no longer available to the public, service charge increases were to be based on a fair proportion of the landlords costs, determined by an independent surveyor. The parties agreed to obtain a preliminary ruling on the question as to whether the RPI had ceased. A study of the RPI showed a change in the commodities used since the date of the leases, and two changes to the base figure since 1960. This meant, inter alia that the stipulation about the addition of £1 for each point the RPI rose, could not be literally applied. Therefore, the plaintiffs