There were a delightful number of bizzare services back in W&W days. These are from the Summer 1999 timetable.
0550 Haverfordwest to Portsmouth Harbour
0855 Pembroke Dock to Brighton (SO)
1543 Milford Haven to Holyhead (SO)
0900 Treherbert to Lostwithiel (arrive 1429)
1915 Birmingham New Street to Barry Island
0749 Weston-super-Mare to Aberdare
0700 Barry Island to Portsmouth Harbour (SO)
1650 Barry Island to Hereford (SuO)
0759 Manchester Piccadilly to London Waterloo (calling at Stockport, Crewe, Whitchurch, Shrewsbury, Church Stretton, Craven Arms, Ludlow, Leominster, Hereford, Abergavenny, Cwmbran, Bristol Temple Meads, Bath Spa, Bradford-on-Avon, Trowbridge, Warminster, Woking (set down only), Clapham Junction (set down only) and London Waterloo (arrive 1406)
1103 Manchester Piccadilly to Penzance (via Crewe, Shrewsbury, Hereford, Bristol Temple Meads, Exeter & Plymouth)
0653 Penzance to Manchester Piccadilly (same route as above)
1325 Penzance to Cardiff Central via Paignton, arrive 2018
1555 Penzance to Birmingham New Street (arrive 2228)
0525 London Waterloo to Penzance (calling at Reading, Swindon, Bath Spa, Bristol Temple Meads, Weston-super-Mare, Bridgwater, Taunton, Tiverton Parkway, Exeter St Davids, Dawlish, Teignmouth, Newton Abbot, Totnes, Ivybridge, Plymouth, Saltash, Liskeard, Bodmin Parkway, Lostwithiel, Par, St Austell, Truro, Redruth, Camborne, Hayle, St Erth and Penzance (arrive 1222)
and many more.