The Fire Precautions (Workplace) Regulations 1997 states
"Fire-fighting and fire detection
4. - (1) Where necessary (whether due to the features of a workplace, the activity carried on there, any hazard present there or any other relevant circumstances) in order to safeguard the safety of employees in case of fire -
(a) a workplace shall, to the extent that is appropriate, be equipped with appropriate fire-fighting equipment and with fire detectors and alarms; and
(b) any non-automatic fire-fighting equipment so provided shall be easily accessible, simple to use and indicated by signs[19],
and for the purposes of sub-paragraph (a) what is appropriate is to be determined by the dimensions and use of the building housing the workplace, the equipment it contains, the physical and chemical properties of the substances likely to be present and the maximum number of people that may be present at any one time.
(2) An employer shall, where necessary in order to safeguard the safety of his employees in case of fire -
(a) take measures for fire-fighting in the workplace, adapted to the nature of the activities carried on there and the size of his undertaking and of the workplace concerned and taking into account persons other than his employees who may be present;
(b) nominate employees to implement those measures and ensure that the number of such employees, their training and the equipment available to them are adequate, taking into account the size of, and the specific hazards involved in, the workplace concerned; and
(c) arrange any necessary contacts with external emergency services, particularly as regards rescue work and fire-fighting."
I imagine it would be hard to argue - unless it was a large empty shed - that there is no need to supply fire fighting equipment to a premises to cover this clause.
From memory, a similar clause appears in the RRO due for incorporation into legislation next year.
I hope this answers your question.
Regards
James