Date | Section of line | Broad | Mixed |
| 1 Jan 1852 | Total mileage | 552m 70c | 3m 11c |
| ? Jun 1852 | Swansea north dock branch3 | 0m 34c | |
| 19 Jul 1852 | Chepstow - Chepstow East3 | 1m 0c | |
| 1 Oct 1852 | Oxford - Banbury (mixed) | 24m 15c - | 24m 15c |
| 1 Oct 1852 | Banbury - Birmingham | 1m 0c | 42m 09c |
| 11 Oct 1852 | Landore - Carmarthen3 | 30m 14c | |
| 19 Jul 1852 | Chepstow - Chepstow East3 | 1m 0c | |
| ? May 1853 | Laira - Sutton Harbour6 | 1m 62c | |
| ? Jun 1853 | Aberdare - Canal Head4 | 0m 41c | |
| 1 Oct 1853 | Durston - Yeovil1 | 18m 77c | |
| 2 Nov 1853 | Gelly Tarw Junction - Merthyr4 | 6m 23c | |
| 2 Jan 1854 | Camarthen - Haverfordwest3 | 31m 14c | |
| 16 Jan 1854 | Paddington (London) new station | 0m 20c | |
| 17 Jan 1854 | Cardiff station (mixed)3 | 0m 40c - | 0m 40c |
| 20 Mar 1854 | Over Junction - Gloucester Docks | 1m 16c | |
| ? May 1854 | Bristol - Gloucester (mixed)7 | 32m 0c - | 32m 0c |
| 29 May 1854 | Bristol station (mixed) | 0m 34c - | 0m 34c |
| 24 Jul 1854 | Bullo Pill - Churchway3 | 7m 73c | |
| 1 Aug 1854 | Wycombe Junction - High Wycombe | 9m 71c | |
| 28 Aug 1854 | Highbridge - Glastonbury5 | 12m 38c | |
| 7 Nov 1854 | Gelly Tawr Junction - Cwmaman Colliery4 | 4m 70c | |
| 14 Nov 1854 | Birmingham - Wolverhampton | 12m 58c | |
| 14 Nov 1854 | Frome - Radstock | 8m 19c | |
| 29 Jan 1855 | Newton - Aller (new alignment)6 | 1m 5c - | |
| 2 Jun 1855 | Hopesbrook - Hereford2 | 17m 46c | |
| 15 Apr 1856 | Haverfordwest - New Milford3 | 9m 16c | |
| 2 Jun 1856 | Abingdon Junction - Abingdon | 1m 70c | |
| 30 Jun 1856 | Warminster - Salisbury | 19m 50c | |
| 1 Sep 1856 | Frome - Yeovil | 25m 62c | |
| 8 Sep 1856 | West Drayton - Uxbridge | 2m 51c | |
| 22 Dec 1856 | Oxford - Reading - Basingstoke (mixed + new loops) | 39m 40c - | 41m 07c |
| 31 Dec 1856 | Total mileage | 663m 46c | 156m 24c |
| Metric conversion: 80 chains = 1 mile; 5 miles = 8 kilometres | |||
| Note 1: | Bristol & Exeter Railway | ||
| Note 2: | Hereford, Ross & Gloucester Railway | ||
| Note 3: | South Wales Railway | ||
| Note 4: | Vale of Neath Railway | ||
| Note 5: | Somerset Central Railway | ||
| Note 6: | South Devon Railway | ||
| Note 7: | Midland Railway | ||
Locomotive Class | No. (+/-) | Total | |
| 1 Jan 1852 | Total locomotives | 220 | |
| Star 2-2-2 | 12 | ||
| Fire Fly 2-2-2 | 62 | ||
| Sun 2-2-2 | 21 | ||
| Leo 2-4-0 | 18 | ||
| Hercules 0-6-0 | 4 | ||
| Great Western 4-2-2 | 1 | ||
| Prince 2-2-2 | 6 | ||
| Iron Duke 4-2-2 | +7 | 29 | |
| Avalanche 0-6-0T | 1 | ||
| Premier 0-6-0 | 12 | ||
| Pyracmon 0-6-0 | 6 | ||
| Bacchus 0-6-0 | 1 | ||
| Bogie 4-4-0T | +13 | 15 | |
| Waverley 4-4-0 | +10 | 10 | |
| Victoria 2-4-0 | + 8 | 8 | |
| Ceasar 0-6-0 | + 8 | 8 | |
| Banking 0-6-0T | + 4 | 4 | |
| Standard Goods 0-6-0 | +60 | 60 | |
| B&ER 4-2-2 | 20 | ||
| B&ER 0-6-0 | + 8 | 16 | |
| B&ER railcar | - 1 | 0 | |
| B&ER 4-2-4T | + 4 | 4 | |
| B&ER 4-4-0T | + 6 | 6 | |
| B&ER 2-2-2T | 5 | ||
| VofNR 4-4-0T | + 3 | 9 | |
| VofNR 0-6-0T | + 5 | 5 | |
| SDR 4-4-0T | + 8 | 12 | |
| SDR 0-6-0T | + 4 | 4 | |
| Unclassified engines | 8 | ||
| 31 Dec 1856 | Total locomotives | +147 | 367 |
| Key: | B&ER - Bristol & Exeter Railway VofNR - Vale of Neath Railway SDR - South Devon Railway | ||