Interesting question - I think the answer is one, a solo sailing gold.
Everything else was on wheels, submerged in water or involved four or more feet.
Diving kinda starts that way. Not sure what the target was but considering the cycling and rowing teams are underperforming i think team GB are doing well. Nice to see us doing well in some new sports with a broader range of backgrounds taking part.
Have GB won a gold on two feet yet?