Great Western Coffee Shop

Sadly not an April Fool joke.

Cancellations to services between Swansea and Cardiff Central
Due to failure of the electricity supply between Swansea and Cardiff Central all lines are closed.
Train services running to and from these stations will be cancelled. Disruption is expected until 13:00 01/04.

Customer Advice
Due to a power failure at Bridgend, no trains services are running between Swansea and Cardiff Central. The power failure is expected until mid-day. This also affects Transport for Wales trains so currently there are no options for travel between Cardiff Central and Swansea. Road transport has been requested, but so far is very limited; therefore customers are advised to delay their travel plans in South Wales until this afrernoon if possible. Tickets will be valid all day, and also tomorrow if customers choose to delay their journey. Refunds will also be given if customers choose not to travel, or do so by another means. Our London Paddington to Swansea trains will only run as far as Cardiff Central (operating an hourly service), with little option for onward travel.

GWR apologises for an delay to your journey that this may cause you.

Does anyone know what electricity supply failed ?

Traction current ? sounds a bit unlikely as such supplies are generally duplicated, and I do not recall any widespread National Grid problems. And of course IETS could still run in diesel mode, and other diesel trains.

Local DNO supplies to key stations ?. I would expect that most stations could still be used, at least in daylight.

Local DNO supplies to a signalling center perhaps.

HV fault affecting two signal boxes. 

Thanks for the info.