Donald Macintyre's Sketch: Theresa May pours cold water on Boris Johnson's cannon

May jumped on the 'gang up on Boris Johnson' bandwagon

Theresa May’s announcement did not go down well with the Mayor of London Boris Johnson in the Commons (PA)

Commons statements can be a chore for the minister involved. But just occasionally they can be a sheer pleasure. Such was 15 July for Theresa May. Because this was “ganging up on Boris” day.

Sensibly she treated with great outward sobriety the tricky case of the three “Ziegler Wasserwerfer 9000”- she pronounced the words with ominous relish - water cannon, prematurely ordered from the German federal police by the London mayor as a precaution against a repeat of the 2011 riots. But the chronology told its own story. As her future rival sat in the row behind her nonchalantly scrawling notes, she recounted, deadpan, how all the police forces in England and Wales had applied to the Home Office for –in Great Britain—unprecedented use of the cannon. She started her lengthy assessment of the issue. But then the Mayor’s office had made the order in June and took delivery of these powerful, if ageing. Teutonic beasts in July. Without a by-your-leave.

Tantalisingly she saved the outcome till late into the statement. It was a resounding “no.” The question had been “serious.” “Water cannon, without safeguards, have the capacity to cause harm.” she explained. Rather like the mayor himself she might have added, There were risks “of primary, secondary and tertiary injuries, including musculoskeletal injuries such as spinal fracture, as well as other serious injuries such as concussion, eye injury and blunt trauma. “ This is apparently OK for demonstrators in Northern Ireland, where water cannon is authorised. But not this side of the Irish Sea .

By now we were lost in an acrostic maze.The question had been reviewed for Committee on the Medical Implications of Less-Lethal Weapons - SACMILL . But the upshot was the same. For it also turned out that Boris’s new toys were 25 years old and required 67 separate alterations and repairs before deployment. .

Boris himself was –relatively —stoical. . He politely thanked the Home Secretary for the “care and thoroughness” of her decision with which “I do not necessarily agree.” He pointed out that he had the “strong support” of the Met’s Commissioner --and indeed the Prime Minister. And then had his dig. “”I fail to see the physiological difference between the people of England and Wales, and the people of Northern Ireland—I will read her study with great interest.”

But it was to no avail. A couple of other Tory MPs were dismayed by Ms May’x decision. But Shadow Home Secretary Yvette Cooper was delighted, Had the vehicles not cost the Greater London Authority £218,00, she asked, adding woundingly: “Given that the Chancellor has now grounded the Mayor’s airport ambitions. may I strongly welcome her comprehensive pouring of cold water on his cannon ambitions, too?

Alex Salmond suggested that like councillors of old the Mayor should be personally surcharged for “buying antiquated, expensive, dangerous, and now totally redundant…. water cannon….aided and abetted by the Prime Minister." Ms May was statesmanlike. Policing was a devolved matter. But you couldn’t help thinking that inwardly, she was screaming “Yes.”