An update from the
FGW▸ website on the 'obstruction on the line':
Line problem in the Severn Tunnel Junction area.
Train services between Bristol Parkway and Newport South Wales have been disrupted due to an obstruction on the line earlier in the Severn Tunnel Junction area. Engineers have worked as fast as possible to restore services to normal. Delays of up to 30 minutes may still occur.
Still not clear what the 'obstruction on the line' was, nor whether the 'operating incident' refers to the same thing?