Remember, the IMC is a National rating and therefore the IMC didn't change with the coming of JAA / JAR.
The CAA recomendation used to be to alternate the IMC renewal between ME and SE if you flew both. This incidently was also their recomendation for the IR renewal before JAA / JAR. Now, the IR has to be renewed on a ME aircraft each year (c.f. 13 months previously) to remain valid for ME.
Oddly enough, there is something in the IMC renewal that you don't have to do for the IR renewal. If you want to renew your IMC at the same time as your IR you have to make this clear to the IRE before the flight test.