Being Leader of the Opposition, to go all American for a moment, sucks.

Winston Churchill reckoned being shot was a kindness by comparison, while Neil Kinnock likened it to purgatory. Yet on election night the worst job in British politics can become the best, from leader of Her Majesty's Opposition to premier. Only it's a hard slog, if it's achieved at all.

Ed Miliband is the Labour Party's 19th leader (all his predecessors, with the exception of Gordon Brown, have had spells in opposition). He may, or may not, become his party's seventh prime minister. A recent Centre for Opposition Studies survey, for example, ranked Miliband the 11th most effective opposition leader since 1945, not exactly a ringing endorsement.

I've never quite been convinced Miliband has what it takes. It's often said voters make up their minds about a party leader within his or her first 100 days, something Kinnock acknowledged when he reflected there was an 'innate feeling among some voters that they could not see me as prime minister'. It was 'just there', he added ruefully, 'in the biochemistry'.

The Miliband life signs are similar; he just doesn't feel right as a prospective Prime Minister. It shouldn't matter but it does: he looks a little unusual and sounds a little odd. I used to think this was just a presentational problem before encountering him as a reporter - in truth there isn't much between the public and private Miliband.

But by the admittedly superficial measurement of this columnist's judgment, last week for Miliband was a success. His speech at Battersea Power Station capped what the Financial Times called 'a remarkable political regeneration', while his recent policy announcements set the political weather with distinctly left-of-centre agenda.

Visiting Edinburgh, Miliband contrasted this with the SNP's policy platform, attacking Alex Salmond's 'unfunded' corporation tax cut and refusal to back his energy price freeze. The Labour leader also mocked his ambition to make an independent Scotland a 'progressive beacon', arguing that 'separation' would present a 'threat' to UK-wide 'social justice'.

Now of course the Labour leader caricatured SNP policy (the Nationalists are certainly to the left of Labour on immigration, although both parties use opposition to the bedroom tax to appear more progressive on welfare than they actually are), but in several important respects he has successfully outflanked the SNP on the left.

For Miliband regularly speaks of 'broken' markets, taking on 'powerful vested interests' and a crisis in the 'cost of living', all of which indicates that the 2007-08 financial crash has changed his view of the world. By contrast, Salmond's fundamental economic beliefs have altered not one jot since the meltdown.

But a coherent policy agenda does not an election victory make. Labour's problem remains its chief messenger rather than its increasingly cogent message, and another weakness is the Scottish Labour Party. While the UK party's policy review (led by Jon Cruddas, of which more below) has yielded creative and potentially vote-winning policies, a similar review north of the border - ongoing since 2007 - has produced next to nothing.

Sure, Johann Lamont made a welcome (if not fully formed) intervention on spending priorities during a prolonged period of cuts (unfairly represented as her 'something for nothing' speech), but there was no detailed follow through, and what the SNP inevitably branded her 'cuts commission' was virtually stillborn. The Scottish party remains fixated on September 2014 rather than May 2016, which may prove a strategic mistake.

Miliband, meanwhile, appears uncomfortable with constitutional politics. In his Edinburgh speech he warned of 'an end to the union of the United Kingdom, where we support each other, wherever we are from'. That's a reasonable pitch, but he also spoke of 'One Nation Labour', which is more problematic.

I remember watching Miliband's 2012 conference speech and being left with the unmistakable impression that the 'One Nation' in question was England. Even the party's conference branding - a stylised Union flag - emphasises the St George's Cross. Similarly, when I heard Cruddas flesh out the party's thinking at Queen Mary, University of London last week, he repeatedly referred to the 'English socialist tradition', substituting 'British socialism' only in name-checking Ramsay MacDonald.

An audience member pointed out the obvious, that 'One Nation' needed more explanation, but Cruddas did not tackle her point. His topic was George Lansbury, Labour's ninth leader (and actress Angela's grandfather), and he wielded a copy of Lansbury's book 'My England' for illustrative effect. Yet seven of Lansbury's eight predecessors were Scots; Cruddas's 'English socialist' tradition is thoroughly Scottish.

This is odd, for Labour has the strongest political claim to representing 'One Nation'. But at the same time One Nation is in fact four, and Labour - Scottish and UK - still lacks a coherent narrative that both acknowledges and promotes that constitutional fact.

Yet neither Miliband's generally dire approval ratings nor his constitutional unease are insurmountable barriers ahead of the 2015 and 2016 elections. His cost of living narrative is a good one, for it resonates even if economic recovery continues into 2014 and beyond. The Conservatives will inevitably depict Labour as lurching back to what David Cameron calls '1970s-style socialism', but it will only resonate if voters consider that a bad thing.

Republicans cast Bill de Blasio, the new Mayor of New York City, in a similar light, but he won by a landslide. And while any comparison between US and UK politics ought to treated with caution, Miliband is clearly taken with de Blasio's campaigning themes of 'one city' and putting an end to the 'affordability crisis'. 'Those who will win in the future', predicted the Labour leader in his Edinburgh speech, 'are those who can address these issues'.

Successful leaders of the opposition also have to convince voters that they look more like the next Prime or First Minister than the incumbent, a task performed with skill by Tony Blair prior to 1997 and Alex Salmond in the run up to 2007. In this respect, Miliband - judging by his approval ratings - still has a leadership mountain to climb.

Beyond that, it is worth considering three rules from Nigel Fletcher's 2011 book 'How to Be In Opposition'. The first is 'have a strategy and stick to it', the second 'have discipline and instil a sense of purpose in the party so it's seen as an effective alternative government', and the third is don't 'oppose for opposition's sake'. The current Leader of the Opposition is doing pretty well on the first and second, not so well on the third, but he has a year-and-a-half to seal the deal.