This policy becomes active on 1 November 2012. From this date government bodies
must adhere to the Open Standards Principles - for software interoperability, data
and document formats in government IT specifications.
Government bodies - in the context of this document, these are central government
departments, their agencies, non-departmental public bodies (NDPBs) and any other
bodies for which they are responsible.

From what I gather, Schools and Local Authorities are 'encouraged' to adopt these principals, but they are mandatory for DfE