Any person authorised in writing in that behalf by a relevant authority may at any reasonable time—
enter upon any land or vessel for the purpose of—
performing any function conferred on the authority or that person by virtue of this Act, or
determining whether, and if so in what manner, such a function should be performed, or
determining whether any provision of this Act or of an instrument made by virtue of this Act is being complied with;
carry out such inspections, measurements and tests on the land or vessel or of any articles on it and take away such samples of the land or articles as he considers appropriate for such a purpose.
If it is shown to the satisfaction of a justice of the peace on sworn information in writing—
that admission to any land or vessel which a person is entitled to enter in pursuance of the preceding subsection has been refused to that person or that refusal is apprehended or that the land or vessel is unoccupied or that the occupier is temporarily absent or that the case is one of emergency or that an application for admission would defeat the object of the entry; and
that there is reasonable ground for entry upon the land or vessel for the purpose for which entry is required,
then, subject to the following subsection, the justice may by warrant under his hand authorise that person to enter the land or vessel, if need be by force.
A justice of the peace shall not issue a warrant in pursuance of the preceding subsection in respect of any land or vessel unless he is satisfied—
that admission to the land or vessel in pursuance of subsection (1) of this section was sought after not less than seven days notice of the intended entry had been served on the occupier; or
that admission to the land or vessel in pursuance of that subsection was sought in an emergency and was refused by or on behalf of the occupier; or
that the land or vessel is unoccupied; or
that an application for admission to the land or vessel would defeat the object of the entry.
A warrant issued in pursuance of this section shall continue in force until the purpose for which the entry is required has been satisfied.
In the application of this section to Scotland—
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Any reference to a justice of the peace shall include a reference to the sheriff.