Complex sentence: One of the organisers of these demonstrations, the well-known radical Tariq Ali, claims to recall an approach by someone representing the "Angry Brigade" who wished to bomb the embassy; he told them it was a terrible idea and no bombing took place.
Split into simpler sentences: One of the organisers of these demonstrations was the well-known radical Tariq Ali. He claims to recall being approached by someone representing the "Angry Brigade" who wished to bomb the embassy; he told them it was a terrible idea and no bombing took place.