Collateral writer David Hare: I was "scared" by prospect of making full TV series

A lot of people live today without paperwork. As in Dickens, society has a definite underbelly – little seen, little referred to and little explored.

• Former Doctor Who stars John Simm and Billie Piper collide in new trailer for BBC drama Collateral
• Why A-listers queue up to work with David Hare

I wondered, then, why this essential shift in my country turned up so rarely in television drama. I first wrote for BBC television in 1973 (a Play for Today), in the great days when a single play would regularly attract eight million viewers. There were so few channels that you knew up to half the viewing public would sit down on any one night to watch a film on any subject that grabbed your imagination.

In the following years, however many one-offs I wrote, I never attempted episodic television. The scale of it scared me. An hour was hard enough, let alone four. But when my aim became to show how the murder of one Arab refugee in south London could resonate through a whole series of different worlds, I knew I had to swallow hard and settle my nerves.

I wanted to write a thriller that would portray a variety of different British institutions. Some, like the police service and the Labour Party, would already be familiar on the small screen. But I also wanted to write about the church, the Army, the security services and, most of all, about our peculiar and neglected removal system.

There was a scandal in 2015 when Channel 4 managed to conceal undercover cameras inside Yarl’s Wood Immigration Removal Centre in Bedfordshire. They revealed serious abuse, and the inspector of prisons was moved to call it “a place of national concern”. The private company that runs Yarl’s Wood, on behalf of the Government, was forced to commission its own internal inquiry.

Inevitably, a facility where so many women wait indefinitely to hear the outcome of their appeal against deportation – with absolutely no idea of when or whether they might be released – raises serious questions of natural justice. But the reaction to the resulting Lampard report was depressing proof that the mistreatment of detainees was not a matter of urgency either to hardened bureaucrats at the Home Office or to our elected representatives. Out of sight, out of mind.

This new century is surely going to bring us a lot more refugees, asylum seekers and would-be economic migrants. If we persist with locking up detainees indefinitely, the centres are going to get bigger, not smaller. At a time of national austerity, Western societies want ways of protecting their wealth, and to keep the poor outside their boundaries.

Yet the free market theoretically depends on the free movement of people for its vitality, and politicians talk all the time of their belief in unfettered competition.

Still, foreigners who travel the Mediterranean by boat, fleeing from war, poverty and persecution, all seem indiscriminately unwelcome in countries, which feel a threat to their own prosperity. Organisations dedicated to counting numbers arriving here were once suspected to be racist. Not any more.

Donald Trump’s proposal for a wall with Mexico and the UK’s admittedly narrow vote for Brexit can both be seen as evidence of attitudes hardening in the West towards aspirational newcomers. At the very moment when hostility to immigrants is growing, is it coincidence that we are also developing a deep distrust of our own institutions?

We still believe in private virtue, in the goodness of our friends, families and acquaintances, but we’re more and more cynical about the intentions and behaviour of professionals. In opinion surveys, government, business, the banks, the press and lawyers all enjoy record low levels of trust and esteem.

Everyone who was once seen to be serving the public interest is today automatically assumed to be in it for themselves. Even teachers and doctors, still our most respected citizens, are not immune.

What really began to interest me is how hard it must be for well-meaning individuals to do their best within institutions that seem so crabbed in with defensive rules and regulations.

How is it possible for any one person to exercise their own judgement and conscience? How much wiggle room do public servants have left? If nobody trusts you, and everyone is waiting for you to put a foot wrong, how does an ordinary public employee find the space to get on with their job?

These may be weighty themes, but I was determined to keep them fleet and on the move. Narrative drama has enjoyed a well-publicised renaissance in the past ten years, and the best series have always been the boldest, aiming to annexe new subjects.

Television writers will tell you that very few projects move through development at great speed. Collateral did. The BBC was gratifyingly keen to make a series about immigration and did everything they could to hurry it, encouraging me to write under the cosh.

As soon as I finished four scripts, SJ Clarkson came back from America, where she’d been directing Marvel’s The Defenders, to take charge of the filming.

From the very start I’d planned a real ensemble enterprise, with at least eight leading characters. But when the first actor we asked, the great Carey Mulligan, agreed to take on her first big television role in recent years as Kip Glaspie, the detective in charge of investigating the murder, both SJ and I sensed we had the chance to make something special.

In the following weeks, I don’t recall a single available actor turning us down. It turns out that if you take television drama into new territory, then an awful lot of people will want to come with you.

Within a few weeks, we were looking at a cast including Billie Piper, John Simm, Hayley Squires, Nicola Walker, Nathaniel Martello-White, Jeany Spark, Saskia Reeves, Richard McCabe and Deborah Findlay.

I called it the National Theatre of the tube. I would turn up to watch filming and find yet another great actor in front of the lens.

A lot has been written about television replacing film as the vital performing art form of our day. It’s certainly true that the survival of cinema has been threatened by the rise of spoilt auteurs who trash scripts, treat actors as lackies and pretend everything is about their so-called vision. I was thrilled to find television still working exactly as it did 45 years ago when I first started, with a perfect collaborative balance of power between actor, writer, director and crew.

In Collateral, we all came together perfectly to tell the same story: there’s the familiar Britain you see on the surface, which you think you know; then there’s a whole other Britain underneath. Let’s all look at that one.

By David Hare

Collateral is on Monday 9.00pm BBC2