Willing's Alley ran and still runs from 3rd to 4th Streets between Walnut and Spruce. In the 18th century merchant Thomas Willing's townhouse stood on the southern (southwestern) corner of the Alley and 3rd Street, facing 3rd St. It was known as Willing's Alley even then.
Clement Biddle sometimes numbered small alleys the way MacPherson did-- up one side and down the other, numbering sequentially, not alternating sides so that the odd numbers were on one side and the even numbers on the other, as he did the main streets-- and only one matchup on Willing's Alley is not enough to tell which way he did it this time. For some reason MacPherson included listings for "East Willing's Alley"; these, wherever they actually were, are included at the bottom of the 1785 section.
(1785) #8 Willing's Alley, Farmer, Ferdinand, reverend
(1785) #10 Willing's Alley, Timms, Henry
(1785) #11 Willing's Alley, Marshall, George
(1785) #12 Willing's Alley, Ferguson, Hugh
(1785) #14 Willing's Alley, Thornhill, Joseph
(1785) #15 Willing's Alley, Cunningham, Widow
(1791) #9 Willing's Alley, Conyngham, Elizabeth, tallow chandler
(1785) #21 Willing's Alley, vacant or residents would not give name
East Willing's Alley:
(1785) #1 East Willing's Alley, vacant or residents would not give name
(1785) #2 East Willing's Alley, vacant or residents would not give name
(1785) #10 East Willing's Alley, Patton, John
UNMATCHED 1791 LISTINGS:
(1791) #11 Willing's Alley, Dillon, Josiah, coachman
(1791) #13 Willing's Alley, Conrey, Edward
(1791) #15 Willing's Alley, Smith, James, accomptant