The east coast main line as it crosses the Border is one of the better introductions to Scotland.

If you want a quick, comfortable and reliable service to Edinburgh and points beyond, you get a magical piece of track thrown in, seascapes included. On this stretch, there is nothing whatever wrong with the east coast line.

Those are ominous words in this day and age. It isn't broke – and how often can you say that about the railways? – so they want to fix it. As though nothing has been learned from the £50 million debacle of the west coast franchise, plans are announced to return the eastern service to the private sector in less than two years.

So spot the logic. East Coast was the company established by Directly Operated Railways on behalf of the Department for Transport when in November 2009 National Express became the second private company to surrender the franchise.

In simple language, private enterprise has twice failed to make a go of running the line. According to the figures for 2011/2012, the most recent available, East Coast in contrast posted a £7.1m profit, up 7% on the previous year, while paying a £183.6m "premium" to the transport department. In other words, there is no serious financial case that can be made against state ownership.

According to the National Passenger Survey, meanwhile, customer satisfaction with East Coast was up again last month and running at 92%. Audited measures of "customer service delivery" for trains, stations and the people who operate them were, respectively, 95%, 95% and 98%.

Not everything is perfect on the east coast line. Electrification was carried out 25 years back when Margaret Thatcher was in power and openly contemptuous of railways. As though to symbolise the attitude, electrification was done on the cheap – like most of the "investment" designed to make privatisation inevitable – leaving the system in need of serious refurbishment today. A massive "dewirement" near St Neots in February was only the latest example of the problem.

Is that a sufficient reason for privatisation? Or could it be, all other things being equal, that East Coast has been too successful for its own good? No doubt the Government needs whatever cash it can scrape together. It can be no accident, however, that the Coalition means to flog off the east coast line before the next General Election, thus preventing a future Labour Government from embarking on renationalisation.

The Coalition's decision flies directly in the face of public opinion. Even before last October's west coast fiasco, and before it became clear that fares were planned to rise at above the rate of inflation for the rest of the decade, the GfK NOP polling organisation found in September that 70% were in favour of renationalisation. In an MSN survey a few weeks later, the figure rose to 75%.

We have a situation in which a hugely unpopular and fragmented franchising system has led, on the east coast, to two private sector failures. According to the Transport for Quality of Life report published last June, that system of itself costs the country £1.2 billion a year.

It is a system which the Government is incapable of operating, as the west coast farce demonstrated, within the limits of simple arithmetic. It is a system the travelling public, paying the highest prices in Europe, would scrap tomorrow. Yet the Government presses on with privatisation for reasons which are merely political and popular only with City investors.

As the east coast line has shown, renationalisation need cost nothing. A Government only has to wait for franchises to expire, as last summer's report recommended, and take control of services one after the other. It makes financial sense and it is what voters want. Predictably, this means that it is rejected out of hand.

Rail is a public service, but privatisation has not served the public well. A myth about nationalised rail has become what passes for a fact in Westminster. This is the one that says private ownership is always more "efficient", contrary to the experiences of state rail users in France and Germany. The truth, as memories fade, is that British Rail, starved of funds, was more successful than its private-capital successors.

Billions have been made in subsidies – £1.4bn to Richard Branson's Virgin alone when it held the west coast franchise – while fares have increased year upon year. East Coast is proof that an entirely viable alternative to private ownership exists. In what passes for thinking within the Coalition, this only means East Coast must be extinguished.

What's striking is the failure of the three main Westminster parties to recognise a vote-winner. Where privatisation is concerned, the Tories are prisoners of their City backers and their dogmatism. The Liberal Democrats once favoured renationalisation, but changed their tunes when Nick Clegg began to prepare for Government. Labour has made supportive noises over renationalisation since the Transport for Quality of Life report appeared, but as usual the party hesitates.

Some facts are too often forgotten. Nigel Gresley's Mallard might have set the world speed record for a steam locomotive in 1938, but the London and North Eastern Railway (LNER) was nationalised in New Year's Day in 1948 because it, like the other private firms, was effectively bankrupt. LNER and the others of the Big Four were facing bankruptcy, in fact, when Mallard was making its run. Only the Second World War postponed the inevitable.

The abiding argument for state ownership is that some utilities are too important to be left to the whims of the market. Despite that, our political classes have been schooled in the belief that nationalisation is a dirty word and an atavistic habit. An argument could be had over that if the record of privatised rail in Britain had not been one of repeated failures, blind ineptitude and waste.

The proof that it need not be this way can be heard and seen not many miles from where this is being written. But when did proof, far less truth, have much to do with political expediency?