BORIS JOHNSON’S beloved water cannon will be sold on without ever being used.

New London Mayor Sadiq Khan announced he’d offload the £220,000 cannon just under a year after the Home Secretary scuppered Mr Johnson’s hope of unleashing them on the masses.

The former London mayor bought the Met Police the second-hand cannon from Germany before they were cleared for use in case of a repeat of the London riots.

Speaking at the State of London debate on Thursday night, Mr Khan said he’d use the cash from the sell-off for youth services.

“This shows the inability of Boris Johnson to get a good deal — second hand, paid almost a quarter of a million pounds.”

Water cannon have never been used on the British mainland, although they have frequently been deployed in Northern Ireland.

Where the nominally non-lethal weapons have been used serious injuries have occurred.

Green Party London AM Sian Berry said it was a welcome development but that further questions needed to be asked.

“First of all we want to make sure that these weapons are never used on the streets of London,” she told the Star.

Once such weapons are allowed to be used as previous examples have shown, notably with Tasers and plastic bullets, their use can, and frequently has been, abused, she cautioned.

“What I am concerned about,” she said, “is who these weapons are going to be sold to.”

If they were to end up in the hands of despotic regimes such as Saudi Arabia or Bahrain the consequences could be grave, she suggested.

Ms Berry is to raise the issue in a written question during a plenary session of the London Assembly next week.