‘… The Tenant shall forfeit all right and title under these presents and the Lease hereby granted and all transmissions and subleases thereof with all that has followed or can competently follow thereon shall become ipso facto void and null and that without the necessity of any declarator, process of removal or other procedure at law and the leased premises shall thereupon revert to the Landlord and it shall be lawful for the Landlord or any person or persons duly authorised by the Landlord in that behalf to enter upon the possession of the leased premises or any part thereof in name of the whole and to uplift rents, eject the Tenants, Subtenants and occupiers and thereafter use, possess and enjoy the same free of all claims by the Tenant, Subtenants and others as if these presents had never been granted ....’
‘PROVIDED ALWAYS AND IT IS HEREBY AGREED that these presents are made upon the express condition that if the rent or any other payment under this Lease or any part thereof shall be unpaid for twenty-one days after any of the days herein before appointed for payment thereof whether the same shall have been lawfully demanded or not or if the Tenant while the leased premises or any part thereof remain vested in it shall be wound up compulsorily or voluntarily (except for reconstruction or amalgamation) or in the event of a receiver being appointed to any of the Tenant's property or in the case of an assignee of the Tenant not being a corporation shall become notour bankrupt or make any assignment for the benefit of his creditors or make any arrangement with his creditors for the liquidation of his debts by composition or otherwise or if the Tenant or its Subtenants or any other person deriving occupancy from it shall at any time fail to implement or shall contravene any of the conditions, provisions, restrictions and others herein contained then and in any of these events the Tenant shall forfeit all right and title under these presents and the Lease hereby granted and all transmissions and subleases thereof with all that had followed or can competently follow thereon shall become ipso facto void and null and that without the necessity of any declarator, process of removal or other procedure at law and the leased premises shall thereupon revert to the Landlord and it shall be lawful for the Landlord or any person or persons duly authorised by the Landlord in that behalf to enter upon the possession of the leased premises or any part thereof in name of the whole and to uplift rents, eject the Tenants, Subtenants and occupiers and thereafter use, possess and enjoy the same free of all claims by the Tenant, Subtenants and others as if these presents had never been granted without prejudice to any right of action or remedy of the landlord in respect of any antecedent breach by the Tenant, Subtenants and others of any of the conditions in this Lease which irritancy is hereby declared to be practional and not penal and shall not be purgeable at the bar …’
‘It appears to me, therefore, to be quite clear that the windfall which has accrued undoubtedly to the defenders in this case is one which accrued as a result of the contractual entitlement under the irritancy clause. Because the receipt of the windfall is part of a contractual entitlement this does not constitute enrichment as that word is understood in the phrase "unjustified enrichment". On any view the income from which the pursuers retained 22.468 per cent was income obtained from the occupational subtenants and was therefore income derived from the pursuers' occupation of the land as tenants. It is precisely that income which is dealt with in the irritancy clause and it is made perfectly clear in that clause that in future all such income reverts to the landlord.’
‘With some hesitation I have reached the view that it would be wrong to approach the issue between the parties in this particular case simply by looking at the terms of the head lease and sublease in isolation. The very existence and terms of both are explicable only against the background of the original scheme for the development of the shopping centre which was embodied in the 1979 agreement. When that wider context is examined, then in my view it becomes apparent that the defenders' possession of the subjects after the irritancy is in reality different from and greater than the possession which they had before the sublease was granted because the defenders now enjoy the fruits of the pursuers' investment as well as of their own. They are to that extent enriched at the pursuers' expense and, for the reasons which I have given, neither the terms of the 1979 agreement nor the terms of the irritancy clause appear to me to constitute a sufficient basis to entitle the defenders to retain that enrichment.’