Last year I sold a February 1689 shilling for £10.00 and a March 1690 shilling for £24.50. Both were in a slightly rougher condition than yours. It's worth noting that gun money for March 1690 is some of the rarest and for a very specific reason. At the time we used two calendars, full unification with the Gregorian calendar not coming until 1752. The legal New Year began on March 25th, so any coin minted for March 1690 had a validity of just eight days.