ChD 24 October 1986. Proceedings between plaintiff landlords (L) and defendant tenants (T) to determine whether a letter written by (T) headed "subject to contract" constituted a valid counternotice served in accordance with the rent review provisions in an an underlease of a shop in Cardiff . It was for (L) to serve a notice stating his opinion as to the market rent and for (T) within eight weeks of receipt (time to be of the essence) to serve a counternotice stating his opinion as to the market rent. If (T) did not serve a counternotice within the time limit the amount stated within (L)`s notice was to be the market rent. If (T) served a counternotice within the time-limit the parties were to seek to agree the market rent within seven weeks of the landlord`s receipt of the counternotice. If they failed to agree (L) would apply to the RICS to appoint a surveyor as expert. (L) served a notice proposing a rent of £36,000pa. After correspondence about comparables, (T) sent a letter bef