ETP-1 (or Electronic Test Pattern One) was a test card designed and used by the Independent Broadcasting Authority (IBA). After test transmissions from the IBA's Engineering Regional Operations Centre (ROC) in Croydon from 1978 it was phased in on ITV over a period starting from 1979, replacing Test Card F. After ITV went 24 hours in 1988, the card ceased to be seen on the channel.
It was also seen extensively on both Channel 4 and S4C during both the pre-launch tests and during the downtime of those channels, due to their limited hours early on. After launch, it was alternated with in-vision teletext services from ORACLE and 4-Tel/Sbectel. On these channels, it was captioned either IBA:CH4 or IBA:S4C, with lines above and below this indicating the card was being generated by the channel, the absence of these lines meant it was generated at the transmitter. After the splitting up of the IBA in 1990, the captioning was changed to NTL:CH4/NTL:S4C. ETP-1 was last broadcast on December 31, 1992 after which Channel 4 showed 4-Tel on View and gradually increased its late night programming - eventually going 24 hours a day in 1997. S4C now broadcasts black screen and tone when off-air.