After years of researching and writing about historical events, working as a consultant on a film project can sometimes help answer questions and solve conundrums by dropping you into the middle of the action.

A British military report dating from May 1940 describing how a vital radio transmitter had broken down due to “sand in the generator” had long puzzled me. Working on Christopher Nolan’s movie, Dunkirk, it finally made sense.

How, I had wondered, had this essential piece of kit been allowed to clog with sand? Had a hapless serviceman dropped it on the beach and feigned innocence? The explanation came suddenly as I stood by the sea near the Dunkirk mole in northern France. The wind suddenly picked up and sand began blowing ferociously into eyes, ears, mouths and anything left unprotected.

Nobody, I realised, had dropped the transmitter. Wind and sand had wrecked it. The landscape retained the story. The same was true as I began work on Steve McQueen’s new film, Blitz, starring Saoirse Ronan with Kathy Burke, Paul Weller and Stephen Graham, plus newcomer Elliott Heffernan, 11, as an evacuee.

This strange period, lasting from September 1940 to May 1941, came alive as I walked around the skeleton of Coventry Cathedral, smashed to pieces by the German Air Force on the night of November 14, 1940. More evocative still was a claustrophobic mediaeval vault under Southampton High Street in which two dozen shelterers were killed at the end of the same month. Stepping inside, 84 years later, the sense of bleakness and loss almost took my breath away. Yet it was not just real locations that affected me.

The Café de Paris, an iconic nightclub and restaurant in the heart of London, was painstakingly recreated for the film – and its resurrection was both magical and somehow terrifying. Waiters swept across the room. Women, hair in updos, sipped champagne and gossiped. Dancers moved around the floor as a band, led by Ken “Snakehips” Johnson, played.

This was as everything was on the night of Saturday, March 8, 1941, at about 9.45pm when a 50kg high-explosive bomb dropped by the Luftwaffe exploded – killing Johnson and more than 30 others. Until then I had struggled to understand how men and women killed by the pressure of the blast were left unscarred. Now, standing in this confined glittering bunker, it made perfect sense. The mystery was how anybody survived at all.

In a sense, I have been researching – and living – this period since I was a boy. It was not unusual for my father to remove an Elton John record from the hi-fi and replace him with Winston Churchill’s collected speeches. I knew Dad had been evacuated to Hertfordshire at the start of the war. He was eventually fetched back home to London where, unlike other family members, he gloried in the bombs and the danger. It was, he used to tell me, the most exciting time of his life.

Even at a young age, I was aware this was just one perspective. In the years since, I have had countless conversations with members of the Blitz generation – and their memories and perceptions reveal a limitless spectrum.

It’s a lesson for anybody who engages with history. It may be convenient to tell a single story, but no such thing exists. The Blitz gave rise to contradictions that have long been papered over.

The period has become a shorthand for a kind of British pluckiness, a “not giving in” or “two fingers” to Hitler. And, to a degree, this was true. The nation, after all, was not bombed into submission. Nor was the famous “Blitz Spirit” entirely a myth. Good humour, concern for others and a sense of sacrifice were instinctive reactions to the raised temperature.

But these were not the only reactions. London in 1940, wrote Quentin Crisp, “became like a paved double bed” as sexual activity proliferated. And there were darker consequences, too. Crime – from inadvertent misdemeanours to the most serious offences, murder, robbery and rape. And sometimes both ends of the rainbow were visible at once.

A burglar, making his way out of a bombed building, saw a child stuck in a burning house and risked his life to rescue her. Congratulated by a policeman, he could hardly get away fast enough.

All of this has been taken to heart by Steve McQueen, Blitz’s director. He understands that people from the past were both the same as us and different. At the start of the war, children were evacuated into the homes of almost any strangers who would have them. This would be unthinkable today – but it doesn’t mean their parents loved them any less.

Just ask the members of the British Evacuees Association, which still represents 500 of those who were sent away. At the same time, certain things have changed less than we might think. London, for example, was a surprisingly cosmopolitan city in late 1940. As well as existing communities (Afro-Caribbeans in Canning Town and St Pancras, Chinese in Limehouse), people had begun arriving from the Commonwealth and from Nazi-occupied nations.

Yet this diversity does not fit the received wisdom. Upon realities such as these, McQueen has built a vivid world that is true to the original.

The Café de Paris is one example. But not only was the living club recreated, so was the subsequent wreckage and the arrival of looters in the bomb’s aftermath. (The ruthless looting amid the blood-stained rubble was described by a policeman, Ballard Berkeley, one of the first on the scene. Berkeley was also an actor who, many years later, would play the Major in the classic 1970s sitcom Fawlty Towers).

Many other slices of reality feature in the film. We see how members of the public, denied the use of the London underground by the Government, forced their way down on to Tube platforms where they would shelter during raids for the rest of the war. We spend time in a Stepney air raid shelter brilliantly run by Mickey Davies, a real-life local optician fondly known to locals as “Mickey the Midget”.

For me, though, the most memorable borrowing from fact is a character named Ife, a black air raid warden whose story mirrors that of Ita Ekpenyon, a Nigerian law student in Britain who became one of Marylebone’s senior wardens. He remained in Britain until his death in 1951.

I will never forget sitting with Benjamin Clementine, the actor playing Ife, discussing his character’s role. A warden would learn where people lived and where supplies and potential dangers were located. He or she would patrol the area to enforce the blackout. Falling bombs had to be reported, emergency services co-ordinated, and shelters organised. But these were just the mechanics.

Beyond them were the gruesome sights, the intense danger and a rarely discussed pastoral role. Benjamin’s character would have been a father-confessor and guardian angel for a large number of scared people. But, for a few, he would have remained little more than a man of colour interfering in their lives. Little wonder our discussion became emotional.

Another part of my job was to draw attention to the unexpected. I shared a fireman’s description of a hose going out of control, an incident that features at the start of the film.

Here was a metaphor for the chaos and mayhem that suddenly overtook millions of predictable lives. Ordinary people, like contestants in a modern-day reality show, were given a few days of cursory training, and turned into firefighters. Except this was no reality show. The cost of failure was not a televised eviction. It was death. Before the Blitz, firefighters were regarded as shirkers, too cowardly for the army. But once the bombs began dropping, they became overnight heroes, idealised subjects of feature films and magazine spreads.

It’s impossible, working as a consultant, not to disappear into the period. I was present on set for perhaps half of filming days and had to make sure that things taken for granted in 1940 were not now forgotten. Blackout for example. People did not show lights – not just out of duty but because it was commonly (if erroneously) believed that a match lit in a telephone booth could be seen by German bomber crews.

Being a nit-picker in an environment where time and money were constantly watched did not necessarily make me popular with everybody. And I had to remember a film inspired by the past is ultimately a work of the imagination. There has to be a balance between fact and fiction.

But one minute I would be talking to the director, the next to supporting artists (the correct term for extras). On one memorable occasion, I stood in the pulpit of the magnificent Christ Church Spitalfields speaking to 100 people dressed in period costume. In a sense I was giving a sermon, telling them how to think and act.

It became clear these supporting artists adore what they do. One man told me he had left his house at 1am to arrive at 5am in time for filming. When I sympathised, he shook his head. He was doing, he said, the thing he loved.

Some were eminent in other fields. On one single day I met a retired judge and a Royal Air Force squadron leader. Another supporting actor was my cousin, Marshall. I had brought him in to play a Jewish worshipper. During a lull I overheard him saying he was standing in for my late father.

My father would have loved the experience. Though he might have interrupted filming to make suggestions. Perhaps it was better that his nephew replaced him.

I always think it is difficult not to be interested in history. It is, after all, the story of everything that has ever happened and everyone who has ever lived. To be uninterested suggests an absence of curiosity in the business of being alive.

Sometimes people proudly declare that they do not look back, only forward. But how can we make sense of the present or plan for the future without an awareness of the past?

How can we understand what is happening in the world today without any historical context? In Alan Bennett’s play, The History Boys, a character defines history as “just one f****** thing after another”. Very true. But it is these things that have made us who we are as individuals and as a nation.

Steve McQueen’s new film helps us to make sense of today’s world. From the experience of people of colour to the knife-edge relationship between Blitz Spirit and bad behaviour, it conjures a world that existed. It does not make the past too easy.

As someone said to me about historical drama, it has to “smell right”. Blitz smells right.

?? Blitz is out now in selected cinemas and available to stream on Apple TV+. Joshua Levine is author of The Secret History of the Blitz (Simon & Schuster)