The stunt caught the imagination of the newspapers. They ed Patey, who confirmed explicitly once again that black people were not welcome to serve on his fleet.

"We don't employ a mixed labour force as bus crews because we have found from observing other bus companies that the labour supply gets worse if the labour force is mixed," Patey told the Evening Post.

In an editorial, the newspaper strongly condemned the policy.

But it did not lay all of the blame on Patey and his management. The TGWU, it alleged, was not doing enough "to get the race virus out of the systems of their ranks and file".

As the national as well as the local media began to take notice of the boycott, the focus was about to shift towards the drivers and conductors.

The bus crews and their union were caught off-guard by the boycott.

For as long as most of the younger staff could , the absence of any black colleagues had been an unmistakable, if rarely acknowledged, fact.

"I never worked on the buses with black guys," says Bishop, who had previously served quite happily alongside black colleagues in other workplaces. "I was a member of the union but I didn't give it much thought - I wasn't directly affected.

"I was always a union man. I being of the opinion - well, it's the union, and they're of the same mind."

At first the TGWU's regional secretary Ron Nethercott - at the time dubbed "the most powerful man in the West Country" by the local media - publicly declared that the crews would have no objection to black labour ing their ranks. He was soon contradicted by drivers and conductors who told the media they would refuse to serve alongside non-whites.

However, Nethercott, now aged 90, insists the bus workers were not motivated by colour prejudice but by a fear that their income would be eroded.

Basic wages on the buses were relatively low by Bristol standards. Before the war they had matched those of skilled workers at the city's British Aerospace plant, but had since fallen behind.

To match the standards of living of their neighbours, bus crews invariably volunteered for overtime.

According to one ex-conductor, it was common to work from 04:30 or 05:00 each morning until midnight. Most aimed to clock in 100 hours a week, which would raise their take-home pay to £20 - just above the average weekly wage in the early 1960s.

To be guaranteed this much overtime, however, the bus crews' rotas had to be understaffed.

At the same time, management had raised the prospect of "one-man operated buses" (OMOs), which required only one bus worker on board each vehicle to act both as driver and conductor. As a result, many felt their jobs were precarious.

According to Nethercott, it was the threat of having their incomes diluted by a newly arrived pool of migrant labour that motivated the enger Group's to uphold the bar, not racial prejudice.

"Wherever they they came from, Europe, China, Alaska, it made no difference," he says.

"The busmen would have still resented it because they were taking away their overtime. Their wages were so damn low that they depended on overtime to make a living."

Not everyone agrees that the crews were entirely motivated by economic concerns, however.

Tony Fear began working as a "strapper", or a new conductor, at the start of 1961 aged 18. Having served in the Territorial Army he had a number of black friends, and was shocked by what he considered outright racism on the part of his new colleagues.

"The worst were the conductresses, I have to say," Fear recalls. "They were terrible. They'd say a black conductor would eventually become a driver, therefore they'd have to work with a black driver, and the things they could do at the end of the journey, you know? It was terrible. They thought they were wide open to rape. They believed that."

As for male bus crews, the older staff - men in their 40s and 50s who had typically served alongside Commonwealth regiments in WWII - tended not to have a problem with the prospect of black colleagues, according to Fear. It was their younger counterparts who were more likely to be bigoted.

"Where did that prejudice come from in that generation, people in their 20s and 30s? I was saddened by it," recalls Fear.

As voices from outside the depot were raised in opposition to discrimination at the company, Fear voiced his for Bristol's black community: "I was sympathetic and I wasn't afraid to say so." His colleagues listened to him respectfully, but few signalled their agreement.

For all that the union undoubtedly played its part in denying black workers jobs, however, Stephenson believes the ultimate blame for the discriminatory policies lay with the management for having set the of debate.

"The ordinary workers took their cue from the Bristol Omnibus Company," he says.

"The unions were more concerned about their economic situation. They thought the black workers were lower status and would bring about wage decreases - it was economic racism.

"Some of them were racist - they didn't want to work with black people. But it was the management, it was the city council that was ultimately responsible."

The boycott quickly gathered pace. ers refused to use the buses. Marches were held across the city. Depots were picketed.

Students at Bristol University - particularly those in radical groups like the Campaign for Nuclear Disarmament and the Campaign Against Racial Discrimination - swelled the ranks of the protests. Around a hundred of them marched on the TGWU's offices.

High-profile politicians lent their , too. Bristol South East MP Tony Benn - then known as Anthony Wedgwood Benn - declared he would "stay off the buses, even if I have to find a bike". Labour leader Harold Wilson, who would be elected prime minister the following year, told an anti-apartheid rally in London he was "glad that so many Bristolians are ing the [boycott] campaign… we wish them every success".

Sir Learie Constantine, the celebrated ex-West Indies cricketer who was High Commissioner for Trinidad and Tobago, publicly condemned the bus company. So too did diplomats from Jamaica and other Caribbean territories.

The media was lobbied tirelessly by the indefatigable Stephenson. Intrigued by the parallels with the American south, reporters from London headed west and made the comparison, to the embarrassment of Bristol's civic leaders.

They were not the only ones who found the attention uncomfortable. "I was being bombarded or harassed or being set upon by the media," says Bailey, who had a less effusive personality than Stephenson.

And yet as Stephenson predicted, Bailey's quiet dignity made him an ideal figurehead. It wasn't only outsiders who disapproved of his treatment. Public opinion in Bristol itself shifted in favour of the protesters.

In Montgomery, Alabama, the boycott had succeeded in part because African-Americans formed a large proportion of the bus operators' customers. In Bristol their numbers were not so large. Instead, the purpose of the British boycott was to generate propaganda - drawing parallels with US segregation and shaming the authorities - while causing as much disruption as possible.

Pickets of bus depots and routes were a key part of the strategy. Hackett organised blockades and sit-down protests at Fishponds Road in the north-east of Bristol to prevent buses getting through to the city centre.

"White women taking their kids to school or going to work would ask us what it was about," Hackett says. "Later they came and ed us."

Like King's campaign, the methods were strictly non-violent. "I said to everyone, not one stick and not one stone."

In fairness, he says, their opponents responded on the same basis: "They gave us a lot of harsh words but they never harassed us physically."

By now, it was the bus crews who were bearing the brunt of the pressure.

As the summer wore on, the TGWU in Bristol was increasingly isolated.

Their erstwhile comrades in Bristol's other unions were becoming hostile.

At a May Day rally organised by Bristol Trades Council, the bus workers were condemned from the platform while TGWU were heckled and barracked by other unionists for bringing shame on the labour movement.

engers, too, were increasingly voicing their disapproval of the bus crews. "In those days the buses were so important that all they'd want to do was see a bus that they could get on," recalls Fear. "I don't think they cared who drove it or who conducted it.

"People were saying: 'If it was a black driver we'd be on time.' That didn't help. Or: 'Oh flipping heck, if you were a black conductor you'd know where I want to get off.' That caused a lot of bad feeling, it really did."

Nethercott was feeling embattled. Attacked by his own for suggesting they would be prepared to work alongside black crews, he engaged in a public war of words with Stephenson which led to the union leader losing a libel action brought by the young activist.

An attempt to broker a compromise, with a black TGWU member g a statement which called for "sensible and quiet compromise", came to nothing.

"Everybody was scared of it," complains Nethercott, still visibly aggrieved 50 years on.

"The great problem around that time was that people lacked courage. They didn't want to get involved. So it was left to the likes of me."

It was clear something had to give.

"I think the union realised they were losing the argument," says Fear.

On 28 August 1963, 250,000 people marched on Washington DC to demand civil rights for African-Americans. At the Lincoln Memorial, Martin Luther King stood before the crowd and delivered his famous "I have a dream" speech.

"From every mountainside," King declared, "Let freedom ring."

That same day was a momentous one for Bristol, too. On 28 August, Ian Patey declared a change in policy at the Bristol Omnibus Company. There would now be "complete integration" on the buses, "without regard to race, colour or creed", Patey added.

The night before, a meeting of 500 TGWU bus workers had voted to agree to "the employment of suitable coloured workers as bus crews". The boycott had succeeded. The colour bar was dead.

By mid-September Bristol had its first non-white bus conductor. Raghbir Singh, an Indian-born Sikh, had lived in Bristol since 1959. On his first day, he told the Western Daily Press he would wear a blue turban to work because it "goes with my uniform. If I wear a brown suit I have on a brown turban". Further black and Asian bus crews quickly followed.

Guy Bailey was not among them. The rejection he had experienced, and the campaign that followed him, had put him off the notion of working on the buses.

"I felt unwanted, I felt helpless, I felt the whole world had caved in around me. I didn't think I would live through it," he says. "But it was worth it."

Those black and Asian crews might have expected a hostile reception but, says Tony Fear, the most vociferously bigoted conductors and drivers handed in their notice rather than work with non-whites.

The impact of the boycott's success was not only felt by those who gained jobs with the Bristol Bus Company. Stephenson believes the Race Relations Acts of 1965 and 1968, which banned discrimination in public places and in employment, were brought in by Harold Wilson's government to prevent a situation like that in Bristol occurring again.

"I met him at the House of Commons," says Stephenson. "He made it quite clear he was going to do something against racism."

Bailey, Hackett and Stephenson were all subsequently awarded the OBE for the part they played in the boycott.

Their names may not be as recognisable to most Britons as those of King and Parks are to most Americans, but all remain quietly proud of their achievements.

Those who found themselves on the other side of the barricades feel differently.

Tony Fear celebrated when the bar was lifted. Before this, he argued against discrimination with his fellow bus workers, but never went to any union meetings to state his case because he disagreed with the concept of the closed shop. Today, he wonders if he should have done more.

"When you get to my age, you think: 'I should have said this, I should have stood up,'" he says.

Bishop, who now has two mixed-race grandchildren, kept quiet at the time, something he now regrets.

"When I was a callow youth, I wasn't much concerned about it," he says. "But later I felt guilty about it. You get more aware of it as you get older."

Their union eventually voiced its remorse, too. Unite, into which the TGWU merged in 2007, issued an apology in February 2013 for siding with management 50 years earlier.

However obscure the dispute remains today, Britain's post-colonial legacy was shaped by its contortions. It began in a bus company office, when a young man walked up to reception.

Picture research by Susannah Stevens

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