| Thornton to Ickenham | 165.00 mi (265.54 km) |
| Thornton to Ifield | 196.78 mi (316.68 km) |
| Thornton to Ilford | 174.25 mi (280.43 km) |
| Thornton to Ilfracombe | 202.30 mi (325.57 km) |
| Thornton to Ilkeston | 60.81 mi (97.87 km) |
| Thornton to Ilkley | 9.41 mi (15.15 km) |
| Thornton to Immingham | 67.85 mi (109.20 km) |
| Thornton to Ince-in-Makerfield | 35.17 mi (56.59 km) |
| Thornton to Inverness | 271.08 mi (436.26 km) |
| Thornton to Inverurie | 242.03 mi (389.52 km) |
| Thornton to Ipswich | 173.10 mi (278.57 km) |
| Thornton to Irlam | 33.41 mi (53.77 km) |
| Thornton to Irthlingborough | 113.54 mi (182.73 km) |
| Thornton to Irvine | 169.05 mi (272.05 km) |
| Thornton to Islington | 171.57 mi (276.11 km) |
