See CAP 804 Section 5 Part E:
In agreement with EASA, UK JAA and National licences which contained the UK IMC rating for Aeroplanes issued prior to 8 April 2014 that are converted to EASA licences will retain IMC privileges. On a Part-FCL licence the UK (IMC) appears as IR (Restricted).
The revalidation/renewal requirements of the IMC Rating shall apply to all IR (Restricted) Ratings.