Two other people were arrested on Sunday in connection with the investigation.
Moses Edwards, 45, of Wanstead, has been charged with arson with intent to endanger life.
He appeared at Westminster Magistrates’ Court on Tuesday and was remanded in custody ahead of a hearing at the Old Bailey on 5 June.
A 52-year-old woman who was also arrested has been released on bail until August.
Cdr Helen Flanagan, head of counter terrorism policing in London, said officers were “working at pace” to arrest everyone suspected of involvement in the attack.
She asked the public to remain vigilant following the recent increase in the UK terror threat level to severe.
“If you have concerns about someone behaving suspiciously, please report it to us. Your information could help us save lives,” she said.
Flanagan added that counter-terrorism officers continued to work closely with the Metropolitan Police to provide protective security advice and support to organisations, community venues and businesses.