How old is my £5 chair?

I recently purchased this hair as a job lot of old chairs. I believe it may be a dark walnut wood. It has a fiddle back, trapezoid style seat and the bottom half of the legs are cabriole style. 3 of the legs have obviously had some kind of water damage or rot and have been replaed with a metal tip. Only one of the original feet remains. There is no sign of any makers marks. The joints are peg joints. It's 15" wide at te bck and 19" wide at the front. Approx 37" tall and 13 1/2" deep. There is a sticker on the bottom saying circa 1740?