And using dock leaves is an old English tradition, isn't it? So not BS.
I always used to rub dock leaves on nettle stings. It never worked. I even searched out the young leaves just emerging and full of juice, but it still didn't work. Maybe the only benefit comes from the rubbing (= massaging).
An old woman once told us that the best treatment for chilblains was wall pennywort (NOT pronounced 'worrt'. The word 'wort' is pronounced like work, and word, and worth).
It did help with the chilblains, but again, it was probably more to do with the rubbing than with the plant itself.