More builders have died on UK sites in the past decade than soldiers fighting overseas. Calls are growing for tighter safety rules and an end to construction's hire-and-fire culture

The Francis Crick Institute, swiftly rising from a vast building site behind the British Library, next to London's St Pancras station, will be the biggest laboratory in Europe, a glittering "jewel in the crown" of UK medical research, according to ministers.

Keen to share in the project's glory, on Radio Four's Today programme last week the mayor of London, Boris Johnson, even acknowledged that the Crick, as it has become known, is a key part of his plan for a "MedCity", something of a branding wheeze by Johnson to attract "big-pharma" investment to this part of north London and gain him kudos as a political visionary.

The Crick is also where Richard Laco, 31, a labourer from Slovakia, was killed by falling concrete and steel on a cold Wednesday last November.

The construction industry is the most dangerous sector in Britain. There is no trade like it. To put it in context, 448 British soldiers have been killed in Afghanistan since 2001. Over the same period, more than 760 construction workers have been killed on British sites.

It is an industry whose workers have from the year dot suffered from being treated as casual labour, picked up and dropped by companies according to the ebb and flow of the economic tide.

Union involvement by workers has historically been a black mark against their names – sometimes literally in the case of the 3,300 workers condemned to work outside the industry through an industry-run blacklist, often for raising issues of health and safety.

And beyond the headline fatalities on building sites – around 40 in 2013-14, the Health and Safety Executive is expected to report soon – last year there were 2,500 deaths due to asbestos exposure, 500 due to respirable crystalline silica exposure and 200 from diesel exhaust emissions.

In the case of Laco, whose Facebook page advertises his love of hip-hop, the sitcom Frasier and playing basketball, he was killed when one of the building's concrete stairwells fell on him as it was being raised into position.

He had been in and out of construction over the previous decade – Laing O'Rourke describe him as a qualified operative with 10 years' experience – picking up work when other career ventures failed. Laco's CV included a three-month trainee post at Amplify Trading in Canary Wharf, learning to be a trader in futures, as well as stints at the outdoor clothing and equipment store Ellis Brigham Mountain Sports.

However, during the economic downturn he was not able to turn his fluency in four languages and a first-class degree in banking, finance and economics from Middlesex university into the career for which he yearned. So his last days were spent working for a Laing O'Rourke sub-contractor.

Laco's death received little attention in the media. Although, like 90% of construction workers, he was not a member of a union, Unite organised a two-minute silence in his memory outside the site as workers on the upper floors of the Crick looked down. Laing O'Rourke said its staff had unanimously decided to pay their respects in a separate commemoration on the other side of security gates.

A few weeks earlier, Unite officials who wanted to talk to some of the company's employees about redundancy negotiations had been told they were not welcome on the site. Unite officials had been banned, claimed assistant general secretary Gail Cartmail, "and I can't help but think that death is more likely where unions are not welcome".

A spokesman for Laing O'Rourke said the company saw it differently. There is no union ban but, while complying with industry-wide guidelines concerning access for union officials, they will only go so far. "Although union-appointed safety representatives may have an interest in the welfare of their members, we do not believe their involvement will add anything beyond our existing extensive approach, as they do not possess the technical understanding of our delivery approach to fully comprehend and be able to mitigate the safety risks on our projects," a spokesman said.

Within a week of Laco's death, the Crick workers began to build again.

Last month Rene Tkacik, a 43-year-old Slovakian, was 32ft below Holborn in a Crossrail tunnel when he was killed by falling concrete. Then there was Kevin Campbell, 46, killed at a Docklands Light Railway site after being struck by a piece of machinery attached to an excavator.

And yet Laco, Campbell and Tkacik were working for the big companies or on public-sector sites – the safest jobs in the industry, for what that is worth.

Richard Laco, from Slovakia, pictured with his sister. He was killed by falling concrete and steel at the Francis Crick Institute site in north London. Photograph: Facebook

The Health and Safety Executive (HSE), which took a 35% cut to its funding in 2011, told the Observer that it now puts 70% of its diminished resources not into the Laing O'Rourkes of this world, but the small and medium-sized businesses. That's where the real risk-takers operate, they believe.

Take the case of Silviu Radulescu, 31, who was killed just a week into his job as a labourer on a demolition job at a decommissioned prison service headquarters in south London.

Radulescu, who had been working in a car handwash stall since arriving from Romania two years previously, wanted to emulate his younger brother, who was making good money on sites. He was killed in 2011 when he was asked to put aside his duties to help manually raise a broken lift. It fell five storeys when he was standing on its roof.

In February this year, Westminster's coroner's court gave a verdict of unlawful death and the police are considering a charge of corporate manslaughter against his sometime employer TE Scudder (Demolition), according to Helen Clifford of solicitors Leigh Day, who represented the dead man's grieving family.

Flavia Radulescu, his sister-in-law, who lives in St Albans, Hertfordshire, told the Observer that she wants lessons learned. "Silviu wanted to work in construction but this job was as a labourer, just to get some experience," she said. "It was my job to tell his parents back in Romania that he had been killed. I called them, but I just lied. I said he was in hospital, in a coma. For two weeks I couldn't tell them that he was dead – it was too hard. Silviu came here just to have a better life. He wanted to have a family and he would spend lots of time playing with my daughter.

"I was angry, so angry, at the time of his death. But now I just want them to learn, to make sure this doesn't happen to anyone else."

The industry has been dragged kicking and screaming over the decades to change its practices and protect those desperate for work. The Latham report in 1994, commissioned by John Major's government, described industry practices as adversarial, ineffective, fragmented, incapable of delivering for its clients and lacking respect for its employees. Then the Egan report in 1998, commissioned by Tony Blair's government, sought to promote the training of staff down the supply chain and the dissemination of best practice. And in 2001 John Prescott, then the deputy prime minister, organised a summit where change was said to be imperative. And standards were raised; the numbers of fatalities did go down – incrementally.

Lady Donaghy was the woman chosen by Gordon Brown's administration to usher in the next era of reform with a report, published in 2010, on what more could be done. She reported that the construction industry was designed for optimal flexibility, with 40% of workers self-employed, with the proportion more like 90% in London – often dependent on goodwill for their next shift. "Some claimed that they were less likely to report unsafe practices because 'they wanted a job next Monday'; in other words, they were less secure in their employment," she wrote.

Donaghy's report concluded there was little she could do about the casualisation of the industry. She wrote: "The advantages are obvious in that it reduces overheads. Some, but not all, argue that it improves profitability and productivity. The disadvantages are that it becomes more difficult for a safety culture to flourish, worker engagement is weak, employment security and continuity is minimal and training is minimal."

However, she made recommendations to ameliorate the dangers. Companies should name directors who are to be held responsible for health and safety, to ensure the courts can prosecute effectively, she said, at a time when smaller companies were simply going into voluntary liquidation following a fatality and emerging under another name. She also said there should be a full-time minister for construction who should encourage worker engagement with companies due to a lack of union presence on many sites. And the HSE should be properly funded. Donaghy's report, One Death Is Too Many, was welcomed by Brown's administration in March 2010, but then they lost power. None of the recommendations came to pass.

It wasn't just the change of government, though, that put improvements on ice. The recession changed everything, too. The 39 deaths recorded by the HSE in construction for 2012-13 was a record low. But that may well be because between 2008 and 2009 the numbers working in construction were cut by a fifth and output by 17.1%.

Problems that were intrinsic to the industry, causing the high rates of deaths and injuries in the mid-2000s, before the financial crash, have been left unsolved. "Is it a ticking timebomb? Possibly, yes," Donaghy said. "With the upturn there is a danger that people with insufficient skills will be taken on. That's when the deaths and accidents start to take place."

The number of fatalities in the capital, where the clearest signs of growth in the industry can be seen, has doubled from four in 2011-12 to eight in 2012-13, and it is believed to have remained at around that number during the last year, if not higher.

"The green shoots are arriving in London and there are fewer experienced people on site and more pressure to finish jobs and get on with another one," Donaghy said. "That's where a properly funded HSE is really important."

And that's one of the worries of Steve Murphy, general secretary of the construction union Ucatt. In advance of Workers' Memorial Day on 28 April, he has publicised a freedom of information response from the HSE which shows that proactive inspections of sites went down from 11,334 in 2011-12 to 10,577 in 2012-13. The HSE claims that this was rectified in the last year, with 11,255 taking place. Murphy says this is not the step-up in activity that the new economic conditions demand. "I believe there is chaos in the construction industry and deaths will rise," said Murphy.

Heather Bryant, who was appointed chief inspector for construction at the HSE in 2013, lists a series of safety initiatives, but she also recognises the challenges. "Historically, you would expect to see an increase in fatalities and injuries. But one of the things we have been trying to do is work closely with the industry and say: 'Watch out, be ahead of the game. This is what has happened historically, let's make sure it doesn't happen this time.'"