Yes, we've discussed that before. I suspect that they didn't think that anyone would want more than 3 conductors, so really meant "at least 3 x 2.5mm²". In my (limited) experience, there is no problem getting 4 x 2.5mm² conductors into MK ones (and many others).Interesting that MK specify 3 x 2.5 mm², when there is room for 3 x 4 mm².
Kind Regards, John