From Severn Tunnel Action Group :
May Timetable Changes
No drastic changes, though of interest to passengers will be:
East/North bound
Monday to Friday
06.25 Cardiff to Portsmouth Harbour (06.55 STJ▸ ) leaves 5 minutes earlier at 06.20 (06.50 STJ). Will now stop at Patchway (07.03)
07.00 Cardiff to Newcastle (07.25 STJ) will now go to Edinburgh
21.00 Cardiff to Westbury SB▸ (21.24 STJ) No longer runs, but is partly replaced by an additional 21.30 Cardiff to Bristol (21.56 STJ)
Saturdays until 06/09/08
09.00 Cardiff to Newcastle (09.25 STJ) no longer stops at STJ
19.50 Cardiff to Exeter St David^s (20.14 STJ) now terminates at Bristol
Saturdays from 13/09/08
09.00 Cardiff to Newcastle does stop at STJ at 09.25
Sundays
Buses replace FGW▸ trains all day
West bound
Monday to Friday
All XX.19 departures from Bristol now depart XX.21, except the 21.19 departure
16.22 Portsmouth Harbour to Cardiff now stops at STJ (19.15) this is the Bath 18.35/BristoI 1854 train.
17.22 Portsmouth Harbour to Cardiff service only runs as a through train on Fridays. Mondays to Thursdays the train terminates at Bristol although there is an additional 19.59 Bristol to Cardiff , but this train does not serve STJ
Saturday until 06/09/2008
20.22 Portsmouth Harbour to Cardiff terminates at Bristol Parkway at 2304 for a bus forward to Severn Tunnel Junction and Cardiff
Sundays until 07/09/08
Buses replace FGW trains all day.