In an ironic twist, the Mayor's busking campaign hopes to prevent parts of the capital becoming 'no-go areas' for buskers, who currently need a permit to perform in certain places.
Mr Johnson has described the practice as very important to "cultural richness of London".
Speaking to the Standard today, the band's lead vocalist and guitarist Olly Corpe said the group now faced being issued with a court summons in the next six months.
He said: "It was ridiculous. The fact we were selected as the best buskers in London just a few weeks ago makes it even more unbelievable.
"A lot of people are advising us to sue [the police] but we are going to see because we are not really like that."
Band: from left, buskers Sam Rooney, Tommy English, Chris Bent and Olly Corpe (Picture: Alex Lentati)
A Met Police spokesman said the group were arrested for unauthorised and unlicensed street performing contrary to section 54 of the Metropolitan Police Act 1839 without any licence to gather money.
He said they were taken to a central London police station but had since been released with no further action.
Defending the arrest, he said: "Spontaneous unauthorised unlicensed street performing causes anti-social behaviour and is a driver of crime.
"There is strong evidence that this type of street performing attracts thieves as large crowds gather.
He continued: "There are numerous licensed spots across the West End where street performers can perform in a safe and lawful manner."
A spokesman for the Mayor's office was not immediately available for comment.
