Look carefully at the photo above, in fact click through to Flickr and look at the image in its original size. Down at the bottom of the window, flanking the altar on either side you will see two crouching figures. Here is a detail of the one to the left. He appears to be in early fifteenth century civilian dress, and is holding what looks to be a candlestick.
What is he? Well, in the late medieval period is was customary during mass for civilians to come close to the altar and raise large candles or torches at the moment of the elevation of the sacred species. A clerk holding a torch of this sort at the elevation of the Host, is portrayed in the Seven Sacrament window at Doddiscombsleigh in Devon (see below). And I suppose that the two little figures at Friskney represent this liturgical custom. Odd aren’t they.