I think this grapevine speaks the truth,
I found this on the internet re. HDC and it states the following,.
AUTHORISED ABSENCES
5.1 Contractors may authorise one off absences during a curfew period. This annex sets out the circumstances in which this may be done.
5.2 If the absence does come within the circumstances below the contractor should advise the curfewee in writing that an absence within the timescales set out would not be pursued as a violation. The curfewee must provide the contractor with sufficient written proof of the reason for the authorised absence, either 24 hours before the absence or within 48 hours of the absence for emergency absences.
5.3 Absences authorised under this section can only be one-off occurrences or more regular absences that occur less frequently than once a week. If an absence is a regular and unavoidable weekly occurrence, the curfewee will need to apply to the establishment from which he or she was released for an appropriate variation to the curfew licence.
5.4 Types of absences which should not normally be regarded by the contractor as violations
(i) Emergency absences
a) Emergency absences are those for which prior notice is not possible and include circumstances in which emergency medical treatment for the curfewee or his/her immediate dependants is required and emergencies involving the curfewee’s dependant.
b)
Duration - There is no maximum duration; however, in general, most absences of this type must not exceed 8 hours in any one day.
(i) Work
a) For any regular work that will always coincide with part or all of the curfew period, the curfewee will be required to apply to the prison governor for a variation of curfew hours. For shift work,
the curfewee should also contact the prison governor request amendments to the curfew period, where the shift times are predictable and known in advance.
Full details can be found here:
http://www.justice.gov.uk/downloads/offenders/psipso/pso/pso-6700.doc