[2003] EWHC 1994 (Ch), 8 August 2003. The claimant (PW) held the headlease of an office building owned by the defendant (MG). The two Part 20 defendants (BT) were subtenants holding underleases of parts of the building. When the headlease and underleases were granted, the parties were all under a misconception, based on the then accepted case law stated in "Brown v Wilson" (HC, [1950] 156 EG 45) that if the headtenant exercised its right to determine the headlease, the subtenants would be entitled to remain in possession. In 2000, PW exercised its right to determine the headlease. By then, "Brown" had been overruled by "Pennell v Payne" (CA, [1995] 06 EG 152) which stated that, in such circumstances, any subtenancy would also determine. PW claimed a declaration that it was not liable to pay the penalty upon determination of its headlease because the parties had contracted out of the usual rule under which subtenancies terminated with the headlease. The defendant argued that the underleases had determined at the same time, which meant 75% of the building was not sublet and the penalty payable. "Held": the claim was dismissed. As a general principle it was not possible to contract out of the general rule in "Pennell".