The requirement for a valid IR is/was only for the issue of an initial type rating, any subsequent type rating did not require a valid IR.
However looking at the UK CAA website it only says it is required for an initial type rating,and not required for renewals or revalidations but it appears silent on additional types.
Not much help!
PS Just looked in CAP 804, found a reference requiring an ATPL or a CPL/IR to be eligible for a type rating course which may imply if you hold an ATPL you do not need a valid IR but it is not clear.
Last edited by bingofuel; 8th Oct 2017 at 13:29.
Reason: Adding CAP 804 reference