The correct colours for waymarking rights of way are as follows:
Byways open to all traffic: Red
The Countryside Commission arrow is quite distinctive and is unlikely to be confused with another sort of mark or arrow. It is also a neat shape, easy to fit onto narrow stile posts and small signs, and fairly easy for even a not too steady hand to paint.
The arrow is designed to appear from a distance as a blob which catches the eye, with the direction becoming apparent as the walker approaches the mark.
On occasions we use yellow flashes of paint that can be seen over a longer distance