Water-cannon or not? It’s a matter crucial to the constitution

As a mayor, Boris Johnson had the power to buy this weapon but not to deploy it. That tells you how messy British devolution is

Riot police use a water cannon to disperse LGBT rights activist before a Gay Pride Parade in central Istanbul, Turkey

You don’t often see Boris Johnson looking deflated, not even when suspended over the Thames on a zip wire. But the mayor of London looked distinctly out of sorts this week when acknowledging that the water cannon he had bought for the police to use in the event of civic disorder might have to stay in their hangar. The Home Secretary, Theresa May, had refused to authorise their deployment, citing a host of reasons why she judged them unacceptable.

As with much that touches the London mayor, the episode had its comical side. But the disagreement masked something more serious: the Mayor of London has the power to authorise and fund the purchase of water cannon to the tune of several hundred thousand pounds – but not the power to authorise their use. That rests with the Home Secretary, who has now vetoed the use of water cannon anywhere in England or Wales.

This is not a clash of personalities – although Boris Johnson and Theresa May are very different political animals, and potential rivals to boot. It is a clash of institutions, and not the first of its kind.

Probably the most serious came early in Johnson’s tenure, when he sacked the Metropolitan Police Commissioner. The dispute was smoothed over when the then Home Secretary, Jacqui Smith, acquiesced in the dismissal and discussions brought agreement on a successor. The rift was sufficient, though, for Johnson to deny that any constitutional precedent had been set.

And in a way, he was right. No constitutional precedent was set.

But perhaps it should have been. The creation of a new seat of power, that of London mayor (and the election of a strong character to that office), produced a constitutional stand-off that has not been sorted out to this day. Now, you can argue that the contests for power in London have been mercifully few and far between, and that any demarcation disputes are nothing worse than teething troubles that will calm down in an eminently practical, British way. But is this really good enough - at a time when devolution has a fresh wind behind it?

The Scottish National Party’s manoeuvring at Westminster is the obvious example. The party’s attempt to fend off legislation on English votes for English laws on the grounds that some ostensibly English laws affect Scotland succeeded. The SNP effectively held the elected government hostage, just as the Conservatives had threatened would happen to Labour during the pre-election campaign. But the SNP can’t have it both ways. If the party wants the additional devolution it has been promised - and still more if its ultimate goal is full independence - it should start practising now.

Just as critically there is the legislation before Parliament offering regions and cities more devolved powers, so long as they agree to have elected mayors. The rationale is that this will anchor democracy and accountability - which is fine. But it also risks creating the very tensions that arise in London, not just between central and local power (the Home Secretary and the mayor), but further down, between the Mayor of London and individual borough councils.

From planning, to housing through the social care system, there are overlaps, conflicts and cracks. And in planning, the Government has just made the confusion worse. Less than a year ago the Coalition government made a big boast of giving local people a greater say, the hope being that they might be more amenable to new housing if they had more control of what it looked like, where it went and who benefited. Now, that power has been supplemented (negated?) by a new provision that allows central Government to step in if it deems the local authority to be obstructive or taking too long. So who now has the last word?

The conundrums do not end here. There have long been local difficulties stemming from the non-alignment of health districts and council boundaries. In declaring Greater Manchester effectively independent for health purposes - and, as such, a purpose-built laboratory for NHS reform - the Health Secretary has initiated a partial devolution of the NHS. Where does that leave the rest?

Back to local government: the West Midlands is the latest group of councils to come together as a “combined authority”, a super council with new powers to govern the region. But this happened just as Sutton Coldfield is trying to restore its own council. Cornwall is to be the first county with extensive devolved power, including a merged health and social service. Other counties are expected to follow as part of what ministers perversely call their “One Nation commitment” to devolution.

How, though, does such devolution dovetail with political and financial responsibility? Northern Ireland has recently been involved in a stand-off with the Westminster government for exceeding its budget and rejecting cuts. What happens if Nicola Sturgeon cannot pay for what her government is pledged to spend? Without clearer lines of power, we could be spawning microcosms of the EU and Greece.

It is really not a pretty picture. With a push from the new government, the UK seems suddenly to be feeling its way towards federalism but in many different and contradictory forms all at once.

It marks a distinct change of mood from 2004 when the north-east rejected John Prescott’s particular form of devolved power. Whatever the reason, however, such a process cries out for clarity.

Constitutional exactitude may not be very British, but the ad hoc, “whatever works” attitude belongs to yesterday and threatens to store up expensive discord for years to come. If the UK is evolving into a federation, let’s do it properly, decide who has what powers and write it down, as quickly, elegantly and democratically, as we can.