18 September, 2017
This picture could show the Parson's Green suspect leaving home with a homemade bomb in a Lidl carrier bag.
Ms Rudd said: "Following the attack in Parsons Green last Friday the police have made good progress with what is an ongoing operation".
An 18-year-old man was earlier detained in the departure area of Dover ferry port, which is the busiest ferry hub in Europe and a gateway to the French coast.
A policeman stands guard during a search by a police forensics team of a house in Stanwell, Surrey near London on September 17, 2017.
The downgrading means that security services still regard the odds of another attack as "highly likely", with Home Secretary Amber Rudd asking the public to remain "vigilant".
Thirty people were injured in the explosion, none of them seriously, in the wake of the subway blast, prompting the police to stage a massive hunt for those who are responsible for the fifth terrorist attack in the country over the past six months.
Prime Minister Theresa May later raised the terror threat level from "severe" to "critical", meaning another attack is expected imminently. The 18-year-old suspect arrested in Dover is understood to be an Iraqi orphan who moved to Britain around three years ago after his parents died.
He was arrested by the Kent Police under the Terrorism Act and remains in custody at a London police station.
At least eight of the couple's foster children have reportedly been refugees, coming from Iraq, Eritrea, Syria, Albania, and Afghanistan, and the elderly couple were believed to have been helping Surrey County Council with a scheme relocating Syrians.
A manhunt is underway after the improvised explosive device (IED) sent a fireball through a packed London Underground train carriage in south west London, during the Friday morning rush-hour.
