Man! If I had just known about that when I lived in Tennessee. We had so many guineas there that sometimes you had to get out of the car to shoo them off the road.
In 1936, my grandfather earned £3 per week which was average for a working man at that time in the UK. Today the average weekly wage is £400 so based on those figures, 21 guineas would be the equivalent of paying £2800 in today's money....Steve