Birmingham historian Carl Chinn explains the Birmingham pub bombings
The Birmingham pub bombings happened on November 21, 1974, when devices exploded at The Mulberry Bush, in the base of The Rotunda and the nearby Tavern In The Town, killing 21 people and injuring nearly 200.
A bomb warning call was made to the Birmingham Mail, but insufficient time was given for the pubs to be cleared.
The Provisional IRA was blamed but it never accepted responsibility.
Six Irishmen men who became known as the Birmingham Six were given life sentences for the bombings but after nearly 17 years their convictions were quashed after it was finally acknowledged that scientific evidence and their "confessions", which had been obtained through violence, were unreliable.
Families of the victims continue to campaign for a public enquiry into the case, calling for #justice4the21.
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