Does the Equality Act 2010 outlaw pay secrecy clauses?

Section 77 of the Equality Act 2010 renders pay secrecy clauses contained in contracts of employment unenforceable in certain circumstances. While it is not unlawful to include such clauses in contracts, employers need to be aware that they cannot enforce such a clause if the employee in question is involved in a "relevant pay discussion". A relevant pay discussion means a discussion to establish if differences in pay exist that are related to a protected characteristic such as sex.