A pilot with an EASA Licence may not fly IFR unless they also have a valid IR of some description.
As has been the case for JAA licences since 1999!
I've always thought (in the UK at any rate) that anyone could fly IFR as long as they met the restrictions of their license.
A common misconception; since 1999 a new restriction was applied to JAA licences requiring compliance with JAR-FCL 1.175 which stated:
(a) The holder of a pilot licence (A) shall
not act in any capacity as a pilot of an aeroplane
under Instrument Flight Rules (IFR), except as a
pilot undergoing skill testing or dual training,
unless the holder has an instrument rating
(IR(A)) appropriate to the category of aircraft
issued in accordance with JAR–FCL.
Para (b) included National ratings such as the IMC so long as they were confined to the State of issue. Para (a) was transferred to EASA but para (b) was not, hence all the issues with the IMC rating.