Jim Murphy’s comment that the cost of Scottish nurses will be largely be paid for by wealthy homeowners in London and the South East has created a predictable storm. Given Murphy’s Unionist credentials it was surprising he linked taxes paid in one place to services delivered in another. After all, Unionists have always resisted the nationalist argument that revenue from oil extracted off Scottish coasts should not be used to fund services across the UK. Whatever the details of the Barnett formula, the principle that there is UK tax income on the one hand, and UK spending allocations on the other, with neither being hypothecated, underpins the Union. Murphy’s remarks were technically correct, but it was a controversial way of speaking.

Despite the storm, the immediate English impact may actually to be to ensure that more potential Labour voters in London and the South East know that Labour will impose a tax that only a few wealthy people have to pay.

But the incident does highlight a problem that could dog the election campaign. The Scottish Labour campaign will be run autonomously from the Labour campaign in other parts of Britain. So will the campaign in Wales.

Recent days events have shown that this can leave Labour’s campaign in England dangerously exposed. English Labour can be caught running a UK campaign when other parts of the Party are running national campaigns. That’s why we need a Labour manifesto for England.

A largely unsympathetic media will exploit every passing issue, like Murphy’s comments, to the fullest extent. The Tories and their friends will lose few opportunities to claim that Wales and Scotland – where they have little interest – are getting a special deal at the expense of England, and that it’s Labour’s fault. The Barnett formula and the Smith Commission have cross party support, but don’t expect this fact to be high in the Tories’ communications strategy.

Labour can’t afford any situation in which English voters are clearer about Labour’s offer to Wales and Scotland than about Labour’s offer to England.

English voters will be electing both a new Government for the UK – dealing with UK economic policy, foreign policy and EU relations, defence, counter terrorism and security, the great bulk of social security policy, much of research funding, strategic environment issues like climate change – and we will be electing a new Government for England.

The next English Labour Government will deal all those vital issues that are devolved to a greater or lesser extent to the other nations of the UK: schools and higher education, health, transport, environmental policy, agriculture and many others. Much of Labour’s policy review is, in effect, policy for England alone.

An English Labour Manifesto would set out, clearly, what the next Labour Government of England would deliver for our nation. An English Labour Manifesto would also connect with the ever rising tide of English pride and identity. England benefits much more from the union than it costs. An English manifesto is a good place to make this clear and why.

John Denham is the MP for Southampton Itchen