There has been lots of press coverage over the past few months about unpaid work and in particular internships. The Government has recently launched new guidance for interns on the issue of fair pay to help tackle some of the issues around knowledge.
HMRC also appears to be taking a more proactive role. HMRC enforces the national minimum wage on behalf of BIS and has been sending letters out to employers who have advertised interim opportunities or unpaid work. The letter apparently informs them that HMRC are carrying out targeted checks for compliance. You might want to heed such a warning and check your compliance!