A person who likes to suck the chodes of fat ginger people only. In the rare occasion that you get a straight Borthwick, he prefers women in their 40s/50s who are extremely obesewomen with blonde hair who weigh around 30 stone. A Borthwick also likes to dress up in womens clothes and fantasizes about naked chodes.
Alex: Look at that dickhead over there. Eyeing up that fat bitch and the fat ginger kid.
Lewis: Yeah, he is such a Borthwick!