Away from home Overnight and Hardship Allowance’s
(a) A member of a police force in the rank of Constable, Sergeant, Inspector or Chief Inspector shall be paid an allowance of £50, to be known as the away from home overnight allowance, in respect of every night on which the member is held in reserve.
The determination goes on to define “being held in reserve”. It states the following;
(b) Subject to sub-paragraph (c), a member is held in reserve for the purposes of this paragraph if the member is serving away from his normal place of duty (whether because the member has been provided for the assistance of another police force under section 24 of the Police Act 1996 or otherwise) and is required to stay in a particular, specified place rather than being allowed to return home.
(c) A member is not held in reserve if the member is serving away from his normal place of duty only by reason of being on a training course or carrying out routine enquiries.
So as you can see, you only need to be kept away from home overnight. It does not matter if it is within force.
(a) A member of a police force shall be paid an allowance of £30, to be known as the hardship allowance, in the circumstances set out in sub-paragraph (b).
(b) The allowance shall be paid in respect of every night when the member:
(i) Is held in reserve (within the meaning of the definition) AND
(ii) Is not provided with proper accommodation.
(c) For the purpose of sub-paragraph (b)(ii) “proper accommodation” means a room for sole occupation of the member, with an en suite bathroom.