Indeed, thetrout: thoughts are with all those affected by such sad events.

An update, from JourneyCheck:
20:23 Portsmouth Harbour to Cardiff Central due 23:56
This train has not yet departed from Fratton and is expected to depart from there at least 134 minutes late.
This train will be terminated at Fratton at 22:45.
This train will no longer call at Fareham, Southampton Central, Romsey, Salisbury, Warminster, Westbury, Trowbridge, Bradford-On-Avon, Bath Spa, Bristol Temple Meads, Filton Abbey Wood, Patchway, Severn Tunnel Junction, Newport South Wales and Cardiff Central.
This is due to a person hit by a train earlier.
Customers forward on 21:23 Portsmouth Harbour to Westbury which has not yet departed Portsmouth Harbour.
Message Received: 26/01/2012 22:46
21:23 Portsmouth Harbour to Westbury due 23:31
This train will be delayed and is expected to be 97 minutes late from Portsmouth Harbour.
This is due to a person hit by a train earlier.
Road transport will be provided for customers travelling forward from Westbury towards Bristol Temple Meads.
Message Received: 26/01/2012 22:52
22:54 Bristol Temple Meads to Cardiff Central due 23:56
An additional train service has been planned to operate as shown 26/01/12 22:54 Bristol Temple Meads to Cardiff Central due 23:56.
This is due to a person hit by a train earlier.
Message Received: 26/01/2012 22:09