By Shaun Ley
Presenter, BBC Radio 4's World at One
It might seem a little strange for the general secretary of a trades union, especially an avowed left-winger, to put his faith in the House of Lords.
But that is what Billy Hayes, of the Communication Workers Union (CWU) did this week.
Mr Hayes was hoping that the Lords would block proposals for the transfer of part of the Royal Mail to the private sector.
The plans face a bruising battle with the postal workers' union
The union argued that these plans contradicted the manifesto on which Labour fought the 2005 general election (with its assurance that the party had "no plans to privatise").
The CWU invoked what's known as the Salisbury Convention, under which the House of Lords has long accepted that it will not block an explicit policy commitment made in the manifesto of a party which wins a general election and forms a government.
The "people's will" should prevail.
Well, on Tuesday, the Lords allowed the government to press on with its plans.
Privately, I expect that was no surprise to Mr Hayes.
Asking the Lords to block a policy which was not in the winning party's manifesto seems a rather broad interpretation of the Salisbury Convention, which was agreed precisely to prevent a government with a Commons majority from having its way impeded by the unelected house.
I doubt if Billy Hayes was seeking help from their lordships because he believes in the hereditary principle.
Rather, he was firing an early salvo in what is likely to be a long, and bruising, campaign for the government.
In this respect, he's learning from one of his predecessors, Alan Johnson, now secretary of state for health.
He enhanced his reputation when, as general secretary of the CWU, he campaigned against similar proposals by the last Conservative government.
Mr Johnson, who began his career as a postman, now finds himself in the awkward position of having to support a policy very close to one he used to oppose.
Although Labour will doubtless go about it in a different way than the Conservatives proposed in the 1990s, those nuances will be lost in the campaign to come, especially as Kenneth Clarke, for the opposition, has promised Conservative support for the plans, making it even easier for the CWU to paint this New Labour policy as an Old Tory one.
But with the two big UK-wide opposition parties pledging their support, why should the prime minister and his business secretary, Lord Mandelson, worry about union opposition? I think there are two main reasons.
There is not a Labour MP who will not have CWU members in their constituency, and they can be an important element of union representation in local parties
First, the CWU is unusual as a union because its membership is evenly distributed across the country.
It is true that many of the big unions, such as UNITE, which have amalgamated workers from many different trades, have a presence countrywide.
However working in so many different businesses often dissipates their political impact.
The CWU, by contrast, largely represents postal workers, and they are to be found in every town across the country.
There is not a Labour MP who will not have CWU members in their constituency, and they can be an important element of union representation in local parties.
This weekend, there will be a rally in Wolverhampton, the town where postal minister Pat McFadden, is an MP, underlining reports that the CWU plans to put pressure on Labour MPs who have not signed the Commons motion criticising the government's plan.
The second thing which gives postal workers influence is sentiment. Whether it is that word "royal" in the title, or hazy memories of men in uniforms and peaked caps ringing the doorbell and handing over your birthday cards, public affection for the postal service is high. Nor does the record of poor industrial relations seem to have diminished it.
At this point, I should declare an interest. Until his retirement ten years ago, my father was a postman.
It was a job he loved, and living in a small village with a big rural hinterland, he also became an extension of social services.
Lord Mandelson was hit by custard last week - this time over airport plans
During his final years, he drove a van for miles over the moor, delivering the mail (and, unofficially, the odd loaf of bread and pint of milk) to houses so remote that one of them was appropriately named "Desolate".
Of course, most postal workers do not have that kind of experience. Urban delivery rounds are rather less attractive, and mostly on foot. These days the heavy mail sack has been replaced with trolleys.
Mind you, last week, I saw two postal workers having to lift one of those trolleys up and down a flight of steps to get over a railway line. They were not far from the evocatively named Post Office Alley, the sort of street name that underlines the warm glow of nostalgia which can get in the way of rational debate.
Even those unhappy with Lord Mandelson's scheme accept that the status quo is not an option.
As the Conservative MP, and committed eurosceptic, Ann Winterton pointed out in the Commons recently, further liberalisation of the postal service is something Britain is obliged to do under European Union directives.
Member countries are not allowed to protect favoured domestic businesses, so the Royal Mail will have to get used to further competition whether or not the government's plans get through.
Labour MPs who object say at least part of Royal Mail's financial problems stem from an earlier attempt to inject competition.
As a result, private firms now send out most of the letters we receive from businesses and even some public sector organisations, with Royal Mail being paid by them to do the last bit; delivery from local sorting office to home.
Unfortunately, this can be the the most expensive part of the process, and Lord Mandelson has attempted to meet this criticism by proposing in the new legislation that Ofcom, which will become the regulator, should have the power to increase charges that Royal Mail can demand from those companies.
Introducing the legislation in the House of Lords gives the government time to fine tune its plans before they face a more bruising passage through the Commons. But that means more time, too, for the opponents to organise their campaign.
Ministers want the law changed by the summer, mitigating the prospects of a row at the Labour Party Conference in the autumn, and more importantly reducing the chances of it becoming an issue in a general election campaign, which will begin, at most, in a year's time.
Even if the election came sooner, the fact that the policy will have been supported by the Conservatives and Liberal Democrats would make it rather a blunt election tool for the opposition.
Lord Mandelson will, of course, remain Lord Mandelson however the public vote at the next general election. But he could yet find that in politics there is something worse than having green custard substitute thrown at you; it is getting egg on your face.