Portsmouth - Cardiff should resume tomorrow (Friday)
.... but just for a day, as line is part suspended on Saturday & Sunday for Severn tunnel works.
I wonder if GWR▸ were consulted, and said yes to the timing of the works, interrupting just one day after reopening through service was deemed agreeable by GWR
Portsmouth to Cardiff is a bit of an oddball in that the number of through passengers is very low indeed - so disruption towards one end only effects a very few passengers towards the other.
From Cardiff Central - journeys by tickets sold (2023/4)
1st Newport
4th Bristol Temple Meads
17th Bath Spa
50th Filton Abbey Wood
77th Southampton Central
101st Salisbury
110th Trowbridge
138th Westbury
144th Warminster
148th Bradford-on-Avon
152nd Romsey
161st Fareham
173rd Portsmouth and Southsea
194th Fratton
203rd Portsmouth Harbour
222nd Cosham