This puzzle was devised by W.T. Williams. The goal is to discover the age of Father Dunk’s mother-in-law (2 down), but the clues contain so much cross-reference and the grid so many interlocking solutions that practically the whole puzzle must be completed to find it.

The year is 1939. There are 20 shillings in a pound; 4840 square yards in an acre; a quarter of an acre in a rood; and 1760 yards in a mile.

ACROSS

1. Area in square yards of Dog’s Mead

5. Age of Martha, Father Dunk’s aunt

6. Difference in yards between length and breadth of Dog’s Mead

7. Number of roods in Dog’s Mead times 8 down

8. The year the Dunks acquired Dog’s Mead

10. Father Dunk’s age

11. Year of Mary’s birth

14. Perimeter in yards of Dog’s Mead

15. Cube of Father Dunk’s walking speed in miles per hour

16. 15 across minus 9 down

DOWN

1. Value in shillings per rood of Dog’s Mead

2. Square of the age of father Dunk’s mother-in-law

3. Age of Mary, father Dunk’s other daughter

4. Value in pounds of Dog’s Mead

6. Age of Ted, father Dunk’s son, who will be twice the age of his sister Mary in 1945

7. Square of the breadth of Dog’s Mead

8. Time in minutes it takes Father Dunk to walk 4/3 times round Dog’s Mead

9. The number which, when multiplied by 10 across, gives 10 down

10. See 9 down

12. Addition of the digits of 10 down plus 1

13. Number of years Dog’s Mead has been in the Dunk family

Hint: Start with 15 across, and keep your wits about you — most of the clues require some sort of insight or intelligent narrowing of the possible solutions; there’s very little mechanical plugging of numbers. With enough careful, dogged reasoning, it’s possible to complete the entire grid, but it’s stupendously hard.