s 90 Other provisions as to interpretation.
(1) In this Act, except where the context otherwise requires, the following expressions have the meanings hereby respectively assigned to them, that is to say:- “ Air-raid shelter ” means protection, otherwise than by war-like means or by any article of apparel, from hostile attack from the air, and “ an air-raid shelter ” means any premises, structure or excavation used or intended to be used to provide air-raid shelter; . . . “ Appropriate department ” means— in relation to any railway, canal, inland navigation, dock or harbour undertaking, the Minister of Transport; in relation to any gas undertaking, the Board of Trade; in relation to any electricity undertaking, the Secretary of State ; and in relation to any water undertaking, the Minister of Health; “ Civil defence functions ” means any functions conferred or imposed by or under . . . this Act; . . . . . . . . . “Land,” in any provision of this Act relating to the acquisition of land, includes any interest in land and any easement or right in, to, or over land; . . . . . . “ Occupier, ” in relation to any unoccupied land, premises, building or part of a building, means the person entitled to the possession thereof; . . . Provided that, where the estate or interest of any person who under the preceding provisions of this definition would be the owner of any commercial building is the subject of a mortgage, and either the mortgagee is in possession or the rents and profits are being received by a receiver appointed by or on the application of the mortgagee, that estate or interest shall be deemed for the purposes of this definition to be vested in the mortgagee; . . . “ Public utility undertakers ” means any persons authorised by any enactment or order to construct, work or carry on any railway, canal, inland navigation, dock, harbour, . . . , . . . or water undertaking, and also includes persons who, though not authorised by any enactment or order (other than the Public Health Act 1875, or the Public Health Act 1936,) to do so, are engaged in supplying . . . water to the public, and for that purpose make use of pipes or mains laid in any highway; and “ public utility undertaking ” shall be construed accordingly. (2) Any premises occupied, or persons employed, by public utility undertakers who carry on a railway undertaking, shall be deemed, for the purposes of this Act, to be occupied or employed for the purposes of their railway undertaking, unless the occupation or employment is wholly or mainly for the purposes of some harbour, dock or canal undertaking carried on by those undertakers.