One man has been left facing charges over the Parsons Green bomb attack, after three suspects were released with no further action.
Yesterday, Scotland Yard announced that a 25-year-old man arrested in Newport, south Wales and a 30-year-old man who was also arrested in Newport would face no further charges.
A 20-year-old man who was arrested in Cardiff on Monday has also been released without charge.
Only one person, 18-year-old Ahmed Hassan, has been charged in connection with the attack.
Hassan, an Iraqi asylum seeker, appeared at Westminster Magistrates Court on Tuesday on charges of attempted murder and using chemical compound TATP to cause an explosion with the intent of endangering life.
Hassan allegedly bought parts to make the improvised device online and left the train at Putney bridge before the device partially detonated at Parsons Green station on September 15.
Witnesses recalled how a fireball swamped the carriage as the device exploded, leaving 30 people injured, with one woman suffering serious burns.
Hassan, of Cavendish Road, Sunbury, Surrey was arrested the following morning by counter-terrorism officers at the port of Dover.
The teenager, whose parents are believed to have been killed in Iraq, was in the foster care of pensioners Penelope and Ronald Jones, who previously received MBEs for their services to children and families.