CA 3 May 1990. The premises consisted of basement and ground floor of a building. The underlease dated 22 August 1978 had been made between the appellant landlords, S and a company, N, granting a term of 15 years "... called the said term". The lease provided for five rent reviews to be reviewed on the hypothesis of a letting "for a term ... equivalent to the said term". The lease also, contained a user covenant entitling the tenant to vary the use dependant on the landlords consent not to be unreasonably withheld. In 1986 N asked to assign the underlease to L but S insisted on a deed of variation which included a new more restrictive covenant containing no obligation for the landlord to agree to a change of use . Two questions arose. Firstly whether the hypothetical lease was for 15 years from review date or from original lease date. HC held and CA upheld that it should be the latter, consistent with the underlying purpose of the rent review. The second question was whether the leas