Thanks to the Great British Weather, having to dry some of your clothes after a rainy day it's not so uncommon; so here is a strong hook that holds securely onto the radiator, and has many other uses.

The original sizes are for radiators with 70mm and 30mm thickness, but since they work better (and stronger) printed on one side, it's easy to alter one or two dimensions with your slicer.

You notice the round boss in the center or the top part, that has a hole that you can put a metal peg through, i.e. to hold your shoes slightly away from the radiator (because it's not nice to put shoes right onto the radiator) or to hold a longer coat.

I would recommend to print with ABS/ASA or at least PETG, standard PLA is very likely to get deformed by the heat.