| Thornton Heath to Ickenham | 18.24 mi (29.35 km) |
| Thornton Heath to Ifield | 19.60 mi (31.54 km) |
| Thornton Heath to Ilford | 13.71 mi (22.07 km) |
| Thornton Heath to Ilfracombe | 173.76 mi (279.65 km) |
| Thornton Heath to Ilkeston | 119.85 mi (192.88 km) |
| Thornton Heath to Ilkley | 188.63 mi (303.57 km) |
| Thornton Heath to Immingham | 153.02 mi (246.26 km) |
| Thornton Heath to Ince-in-Makerfield | 181.22 mi (291.65 km) |
| Thornton Heath to Inverness | 451.12 mi (726.00 km) |
| Thornton Heath to Inverurie | 416.37 mi (670.08 km) |
| Thornton Heath to Ipswich | 70.72 mi (113.81 km) |
| Thornton Heath to Irlam | 171.63 mi (276.20 km) |
| Thornton Heath to Irthlingborough | 67.37 mi (108.43 km) |
| Thornton Heath to Irvine | 346.25 mi (557.24 km) |
| Thornton Heath to Islington | 9.94 mi (16.00 km) |
