Tim - is that 'stub' clear or is it bluish like the rest of the piece, can't quite make out from the pix - obviously I hadn't looked properly first time around.
In passing, I notice there are some pieces of W/Fs showing in Jackson which have a stub foot/base similar to this one. Of course, I'm not remotely linking this piece to Whitefriars, but the similarity of foot shape with this piece might just indicate the same approximate manufacturing date of 1930s. However, I notice you're suggesting mid C20, so possibly unrelated date wise.