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The spouse, unmarried partner and children of a work permit holder may be admitted to the United Kingdom as the dependants of a work permit holder. The spouse/unmarried partner will be given conditions of stay, which do not place any restrictions, other than those that would apply to a resident worker, on their taking employment or engaging in business.
Therefore, a dependant of a work permit holder is free to work in the UK as long as the endorsement in their passport places no restrictions on them.
http://workingintheuk.gov.uk/working_in ... faqs.html?