Producer/director Mark McMullen on capturing the stories of German British Army veterans.

Production company True North Productions
TX Sunday 26 April at 9pm, National Geographic Channel
Producer/director Mark McMullen
Executive producer Glyn Middleton
Associate producer Anna Dickeson
Summary Churchill's German Army is the story of how 10,000 German and Austrian refugees volunteered to fight for Britain against the Nazis

Bertie Lickorish was with me when we found Lord Haw Haw in the woods ... I only fired once, but made four holes [in him].” When a potential interviewee begins a story like that, you know you have to get him on board - however complex the logistics.

The challenge to complete Churchill's German Army was always going to be one of time constraints. We had three months to research, produce and deliver this one-hour documentary. Our potential interviewee upped the ante by telling us he would soon be leaving for Florida and wouldn't be returning until after we were due to deliver the programme.

Two weeks later, I was in a forest on the German-Danish border with Geoffrey Perry - born Horst Pinschewer - as he explained how he'd shot and arrested the infamous Second World War traitor William Joyce, aka Lord Haw Haw, 63 years earlier. Four holes with one bullet, you ask? He shot the pro-Nazi broadcaster in the buttocks, at a perpendicular angle.

The irony of a Berlin-born British officer shooting a pro-Nazi British national in a German forest is just one of many remarkable stories we uncovered during the research for Churchill's German Army.

Selecting the right balance of people to tell the tale of 10,000 German and Austrian refugees who fought against their country of birth was a real challenge. We were able to tap into the expert knowledge of Helen Fry - author of The King's Most Loyal Enemy Aliens - and meet the surviving veterans with whom she'd built close relationships.

Freelance producer Mark Handscomb did the initial groundwork and we soon had a list of talent we believed could do the story justice, if we could convince them to take part.

The surviving German-born veterans are an incredibly modest group not immediately willing to disclose their own bravery and tragedies. Associate producer Anna Dickeson did a sterling job in getting everyone on side.

Time and budgetary constraints meant dramatic reconstruction wasn't an option. We decided that taking our veterans back to where their stories had unfolded might help to bring distant memories to the fore. But the youngest of our veterans was 86 years old, and getting them to foreign locations in the middle of winter at short notice was a tall order.

We had convinced intelligence officer Geoffrey Perry to return to Germany, then tank driver Willy Field - born Willy Hirschfeld - agreed to return to the Netherlands where he had lost his entire British tank crew in one day.

Willy had experienced the hell of Dachau concentration camp before volunteering to fight for the British. For the first time, he returned to the spot where his Cromwell tank had been destroyed by German guns. We visited the cemetery where his crew was buried - an incredibly emotional day for everyone involved.

Mark McMullen: My tricks of the trade

  • Get to know your contributors before filming - if people are uncomfortable with you off camera, they won't be comfortable on film.

  • Know exactly what you need to get from a filming day, but also know how to adapt to the unexpected.

  • Hotties! (exothermic hand warmers). A godsend when filming in freezing remote locations.

  • Look after your team and contributors. A happy team generates better results.

  • Enjoy it - a little fear of failure is important, but so is enjoying what you do