LONDON - After the collapse of his political dreams, top Brexit campaigner Boris Johnson suffered one final humiliation - the sale of three unused water cannon he bought when he was mayor of London.

His replacement Sadiq Khan said he would sell them off to fund youth services in the British capital.

“This shows the inability of Boris Johnson to get a good deal.... We want to get rid of them,” Khan said, complaining that the city had also had to pay storage costs. Khan said the whole deal “beggars belief”. Johnson bought the three vehicles second hand in Germany two years ago for around £200,000 to deploy them in case of rioting, even though police do not have authorisation to use them in mainland Britain. Interior Minister Theresa May denied the permission last year and mentioned the cannon on Thursday when she declared her candidacy to replace Prime Minister David Cameron - shortly before Johnson failed to declare his own after being wrongfooted by a key ally.

“Boris negotiated in Europe. I seem to remember the last time he did a deal with the Germans, he came back with three nearly new water cannon ,” she said.

Water cannon have only been used in Northern Ireland, not in the rest of Britain. Calls have grown for their use since London and other major British cities were hit by a week of rioting and looting in 2011.