Between 1735 (when peak direct Bath -
STJ▸ services end) and 2135 (when evening direct Bath - STJ services resume) I could only find the following from December 2007.
Via Newport :
1835 Bath Spa - Newport arrive 1925 - 45 minute wait then change into 2010 Newport - Severn Tunnel Junction arrive 2021. Overall journey time 1 hour 46 minutes.
1937 Bath Spa - Newport arrive 2023 - 51 minute wait then change into 2114 Newport - Severn Tunnel Junction arrive 2124. Overall journey time 1 hour 47 minutes.
2035 Bath Spa - Newport arrive 2128 - 49 minute wait then change into 2217 Newport - Severn Tunnel Junction arrive 2233. Overall journey time 1 hour 58 minutes.
Compared with a direct Bath - STJ journey time of around 40 minutes , there would appear to be no contest.
Lets try via Bristol Temple Meads (mininum connection time 10 minutes) :
1900 Bath Spa - Bristol Temple Meads arrive 1915 - 10 minute wait then change into 1925 Bristol Temple Meads - Severn Tunnel Junction arrive 1947. Overall journey time 47 minutes.
1937 Bath Spa - Bristol Temple Meads arrive 1949 - 30 minute wait then change into 2019 Bristol Temple Meads - Severn Tunnel Junction arrive 2046. Overall journey time 1 hour 9 minutes.
2035 Bath Spa - Bristol Temple Meads arrive 2050 - 29 minute wait then change into 2119 Bristol Temple Meads - Severn Tunnel Junction arrive 2148. Overall journey time 1 hour 13 minutes.
Better , but still not great. You could change at Filton Abbey Wood if you wished on the latter 2 journeys , but the wait would be about the same , with nowhere to get a cuppa......
Whatever your feelings towards
STAG▸ (and I detect a little animosity among some members) dont forget that Bath - STJ direct services are being reduced from 18 westbound and 17 eastbound to 5 westbound and 6 eastbound on Monday - Fridays. They feel that such a large cut gives them a legitimate grievance.
That's enough from me anyway. I refer you to the quote below (Jim , I know nobody's blaming me for posting the press release) :
They will be more than happy to answer your queries.