Yes, it did seem the mantle/wings were less reddish than on Greater. (It was an adult.) Irides definitely appeared black to me and the size seemed small--so much so in fact that I thought it was going to be a Oriental Cuckoo or something of that sort.
Agree the habitat is wrong but perhaps there could be some dispersal in autumn in which birds could be seen away from preferred habitat? Greater Coucal is regular here of course.