The published co-ordinates will take you to the Melksham Tourist Information Office from where you should be able to spot the first of the blue plaques. Then locate the other blue plaques around the town (One has been removed but I will let you work out which one) and answer the following questions to determine the position of the final cache and perhaps learn that some interesting things do happen in Melksham...
#1 - The Round House - How many windows does the building have, let the answer = A
#2 - The Red Lion - When was it rebuilt, let the last digit of the year = B
#3 - The Almshouses - How many are there, let the answer = C
#4 - Town bridge - how many lamps adorn its balustrade, let the answer = D
#5 - The Reading Rooms - how many windows are bricked up to avoid tax, let the answer = E
#6 - Second Cottage Hospital - how many blue plaques on the building, let the answer = F
#7 - First Cottage Hospital - How many metal bars on each of the lower row of windows, let the answer = G
#8 - One Bank Street - How many arches, let the answer = H
#9 - New Hall - When did it win an environmental award, let the last digit of the year = J
#10 - The Old Police Station - What number is on the door, let the last digit = K
#11 - Town Hall - Locate the bench marker, sum the digits and subtract ten = L
The cache can be located at: N51 22.(H-J)(A-D)(B+K-L) W002 8.(C-F)(D-E)(G-L-J))