Britain is becoming a 24-hour society driven by an army of night workers: one in seven of the working population operate regularly outside of traditional nine-to-five working hours.
The total value of Britain's night economy is estimated by one think tank to be worth some £244bn, a rise of 30 per cent over the past decade. This trend is expected to accelerate as the demand for 24-hour services and round-the-clock shopping continues to soar.
Research by TBR Observatory suggests Northern Ireland, London and the South West are the fastest-growing regions for night-time economic activity in the UK.
But the world of work that kickstarts at twilight comes at a cost. Doctors are warning of the increasing danger to night workers' physical and mental health. A separate study published last week revealed that night-shift workers are disproportionately susceptible to diabetes and obesity.
"Though legislation prevents night employees working longer than eight hours, there are exclusions that go unreported," said Sukhdev Johal from the School of Management at Royal Holloway, University of London. "Most cabbies are self-employed, most small shopkeepers are likely to be self-employed or in charge of their own hours. Many now work outside their industry regulations, which sets a dangerous precedent.
"The contradiction here is that the Government rhetorically promotes family life, yet in practice, the policies erode the very barriers that protect families. Night working might fit certain lifestyles, but for the majority there's a cost that's not borne by the employer."
Additional reporting by Thomas Norton
Jason Coffey, 22, is an undertaker in Ashton-under-Lyne in Manchester. Start time: 5pm. End time: 8.30am
"When a death occurs at night, it used to be common for people to sit down and sort out a funeral there and then. Now it tends to be more complicated.
"After the Harold Shipman case, there has been far more stringent legislation. There is usually at least three days from the death to the burial. That time allows for a series of checks.
"Our firm is on standby 24 hours. Usually we have a number of crews covering the entire country. As an organisation, we'll do 100 funerals a year.
"Even at night, you have to be prepared. The family expect support and will advise us on what they want to do before the body is finally buried. Usually the family either want the person to be taken to the mortuary or laid out to rest in the house. We are there to provide support during grief and take care of practicalities. But we can't offer counselling.
"Usually we turn up and speak to the next of kin, make sure the body can be moved out of the property, move them to the ambulance, and then head back.
"After the deceased is secured, the staff will go back and prepare for the next call. The next stage of the process is usually the funeral arrangements which we are expected to assist with, in daylight hours.
"The company is careful to rotate workers. Staff that have been working throughout the night are then entitled to time off in lieu. Many firms have realised that working nights is tough and can impact both family life and health."
Marshall Lewis, 49, from Lewisham, south London, has been an engineer on London Underground for more than 20 years. Start time: Midnight. End time: 5am
"I love working at night. Before joining Transport for London I used to be a DJ; playing at house parties and club nights. Now I preside over a team of engineers.
"Each night we do safety checks ensuring the stations' signal systems and mechanics are working properly. There are two core aspects to my job: making sure that maintenance is done safely, and that the work is done properly and to time. As a manager, you need to work especially hard maintaining a night team's motivation. Working at night can be particularly dangerous and you'll invariably get one or two blokes who might have lost sleep with kids or commitments during the day.
"The workforce has changed immensely in the last few years, particularly with the influx of Eastern Europeans. When we first started, we had light bulbs plugged into the tunnels and diesel generators that would light up the area that we were working on.
"The job puts a huge strain on relationships. Night work is extremely stressful for partners and there's no shortage of people with broken marriages. For me it's different; I love my job and anyone I'm with has got to be able to adapt to my working hours.
"The Olympics are going to be a real test. During the Games, TfL is talking about extending Tube hours. There's talk that we're only going to be allowed on the tracks for up to two hours at most. We're certainly set for a challenge, but I know we'll be able to meet it."
Keith Richardson, 53, is a meat trader in London's Smithfield Market where he sells to hotels, shops and restaurants. Start time: 1am. End time: 6am
"In the last decade, hours have got longer, start times earlier and the job more demanding. When I first started working here 25 years ago, we used to open at 6am and have a steady line of customers throughout the day. Since then, traffic in Central London has worsened and the congestion charge has put people off. So our start times have got earlier each year. We arrive now at one in the morning.
"In the past five years, the market has changed. During the boom years, we'd had a continuous influx of clients which would include ordinary people with a hankering for freshly-sourced food. That's all changed. Some of our clients suffered during the recession and many of the businesses we supplied to have since gone under. Now we rarely see members of the general public; instead, we're serving hoteliers and restaurants. And if their business is slow, so is ours.
"Having a family puts a lot of strain on working at night; and I try not to work five days a week any more. I usually have to go to bed at eight in the evening, which can be tough on the family. I am now starting to think about the next stage of life. Perhaps, in time, I might decide to sell the business."
Overnight personal trainer
Gary Reid, 38, is an overnight personal trainer at a 24-hour gym in Stoke-on-Trent. Start time: 7pm. End time: 5am
"Britain's relationship with gyms has changed dramatically in the past decade. It was once considered niche and elitist; then it became mainstream but expensive.
"Now it is mainstream and accessible. I know that because the clients that visit Pure Gym between midnight and 3am are different from anyone I've seen in the gym in recent years. They range from off-duty taxi drivers, ordinary members of the public as well as pub and restaurant workers clocking off for the night.
"Working nights in a gym is tough as it's hard to maintain your diet when your body is taking in food at peculiar times of day. For a personal trainer, looks are important. So I have to fit in my own training schedule as well.
"People's demands have changed, too. Nowadays, people don't just want to come in and do weights; they actually opt for personal training even in the middle of the night. Ten years ago, you would never imagine sitting in a gym at three in the morning discussing fitness goals.
"Much of this is related to the way the night economy has changed. With the gym now more accessible to everyone and more of the country working outside of traditional working hours, there is a growing demand for 24-hour gyms like ours."
Air traffic controller
Nicholas Mason, 41, is an air traffic controller at NATS Prestwick Centre near Glasgow and oversees more than 400 aircraft flying from the US to Europe a night. Start time: 10pm. End time: 8am
"Eighty per cent of traffic from America now flies through UK airspace; and up to 500 planes can pass through British airspace in the space of one night.
"Fifteen years ago, we used to prepare contingency plans for mechanical failures. Now concerns are different; they are more focused around people on board and what they could be capable of. Ever since 11 September, Britain and America have been in much more frequent contact with airspace issues.
"I arrive in the office at 10pm and the first part of the job involves administration. At midnight, I step into the tower where we manage flights. There are seven controllers who work for me. We have to study how airspace is divided and ensure that plans are adequately separated. Between 1am and 5am are the peak hours in which nearly every space has American aircraft passing through. Those moments need intense concentration. One thing we are very careful of is to manage staff's routines carefully so that they're only doing a limited number of nightshifts a month.
"Some workers go out for breakfast once work has ended. It is 9am by the time I go to bed. I will wake up at two in the afternoon and then go to bed at six in the evening for a quick powernap before starting work."
Late-night talk show host
Joanne Good, 57, is a late-night presenter on BBC London. Start time: 8pm. End time: 3am
"Late night radio has changed, as have those that listen to it. In the 1990s, you had to work really hard to drum up a night audience. Sometimes we'd have to call Joe Allen's in New York or a radio station in Botany Bay to warm up the show. Our audience used to comprise the cab-driving community and a plethora of drunk people coming home from nights out.
"Not any more. People's lifestyles have become more nocturnal and digital media has spread our presence far beyond this city. We have a regular audience, some of whom are sitting on beaches in the Turks and Caicos Islands and their offices in Australia listening to us with headphones on.
"In recession-ridden Britain, one of the largest set of new listeners are the unemployed. The 'shock-jock' era is behind us; instead those calling in want to bare their souls.
"Sometimes in London, it feels as if the whole city is awake. We have people who call us while preparing meals or shopping in a supermarket at four in the morning. London has become a late-night village; but its effect is fast spreading around the country.
"In the old days, when I finished a show I'd go home. Now, at 3am I will usually stop in Bar Italia for a coffee or stop in any of the hotel bars, open later than ever before. Many of our guests on the show will leave the studio and hit the town afterwards."