1939 bombing by IRA
The Sabotage Campaign was a campaign of bombing and sabotage against the civil, economic, and military infrastructure of the United Kingdom from 1939 to 1940, conducted by members of the Irish Republican Army (IRA). The campaign resulted in 300 explosions, seven deaths and 96 injuries.
On 17th January 1939 a bomb exploded in Great Barr at an electricity pylon, but it remained standing on one strut.
Ref: https://en.wikipedia.org/wiki/S-Plan