A 23-year-old man suspected of throwing a fire extinguisher at police from a roof during this week's student fees protest has been released on police bail.
The student at Anglia Ruskin University, Cambridge, was arrested after police officers scoured footage of Wednesday's riot, which saw protesters storm Millbank Tower, the home of the Conservative Party headquarters.
The man, originally from Reading, Berkshire, was held on suspicion of violent disorder and questioned at Parkside police station in Cambridge before his release.
Police Federation representatives have called for the person who flung the empty metal fire extinguisher from the roof of Millbank Tower to be charged with attempted murder.
Senior officers said it narrowly missed injuring two territorial support group officers, brushing down the back of one and hitting the knees of another.
The incident was one of the defining moments of the four-hour stand-off after a breakaway group of students attacked the Millbank office complex.
Up to 50 demonstrators smashed windows, discharged fire extinguishers and threw debris from the roof of the building. Hundreds of others gathered in a forecourt below booed the culprit and shouted to others to stop damaging the building and throwing missiles.
The Met have said that ten of the 54 people arrested during sprawling outbreaks of disorder were under 18. A spokesman said most of the others were students, most aged between 18 and 26, and including 33 men and 21 women.