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[1921] 1 Ch 200. The claimant took a Lease of land from the defendant Landlord with the express and known intention of storing explosives on it. The landlord then started to build on neighbouring land; the proximity of the new buildings meant that the claimants could not legally store explosives. The court held that for the landlord to build would amount to a derogation from grant, that is, they would have taken good money to grant a lease which would be of no value to the lessees.