The UK communications regulator has proposed to revoke amateur radio licences which have not been revalidated by the holder.

Currently, UK Amateur Radio Licences remain valid unless surrendered by the licensee or revoked by Ofcom. Last last time Ofcom revoked an Amateur / Ham Radio Licence for any reason was over 9 years ago.

Ofcom require holders to re-validate their licence every 5 years but until Ofcom goes through the formal process of Revocation such licences remain valid.

It is suspected there might be tens of thousands of amateur licences which have not been re-validated, with an estimated 1,000 due to be culled in the first batch of deactivation. Ofcom proposes to start with those that should have been re-validated in 2012.

If Ofcom wishes to revoke a wireless telegraphy licence, it must:

notify the licensee of the reasons for which it proposes to revoke the licence;
specify a period in which the licensee may make representations;
decide whether or not to revoke the licence within one month of the end of that period; and
notify you of its decision within a week of making it.

Ofcom announcement - http://licensing.ofcom.org.uk/radiocommunication-licences/amateur-radio/revalidation/

How to re-validate your licence - http://www.essexham.co.uk/validate-your-licence