What if the Battle of Britain had been lost? What if Germany had invaded and annexed these shores?

Secret Army The story of wartime Britain's mysterious terrorist forces

What if the Battle of Britain had been lost? What if Germany had invaded and annexed these shores? In the first of two parts Lynne Mortimer talks to John Warwicker, the author of Churchill's Underground Army.

John Warwicker knows more about espionage and terrorist threats than most. As a Special Branch officer protecting successive Prime Ministers - Harold Wilson, James Callaghan and, for eight months, Margaret Thatcher - he was constantly in touch with the secret services.

It is his specialist knowledge and understanding of covert operations that have informed his writing and research. But as well as an extraordinary gift for fact-finding, John also seems to have an instinct - almost a sixth sense - for a mystery.

In the case of the Auxiliary Units in the Second World War, it took patience and tenacity to elicit the facts. The true stories in his book Churchill's Underground Army are the stuff of Boys' Own Adventures.

On the home front, in 1940, people believed the Home Guard was our last line of defence against invasion. But, unknown to the general population and all but a handful of our war leaders, installed behind that line and operating under cover of total secrecy were the men (all men initially) of the Auxiliary Units, known as auxiliers.

Recruited in mid-1940, they were trained to kill and destroy the enemy in the event of occupation. While the Home Guard - from whose ranks many of the auxiliers were recruited - struggled to get arms and equipment the auxiliary units were well supplied with weapons and explosives. The patrols were trained and operated individually so that they couldn't give each other away if any were captured.

Their secret mission was to carry out guerrilla operations on British soil in the event of German occupation - a possibility that seemed frighteningly imminent in the early years of the conflict. They were prepared to use desperate methods for desperate times and John says it is clear the Auxiliary Units fell outside the international conventions of war.

He has met and recorded audio evidence from men who were recruited as auxiliers. It wasn't always easy to persuade them to talk. These staunch patriots had been sworn to absolute secrecy and, even more than 50 years after the end of the war, many were reluctant to acknowledge their role in this clandestine army - some wouldn't even confirm its existence.

But his painstaking research, coupled with the trust he engendered in the men and women he has interviewed have resulted in Churchill's Underground Army, his second book about the Auxiliary Units. The first was Britain in Mortal Danger in 2002.

He retired from the Special Branch at the age of just 49 in 1979 and, over the subsequent three decades forged a second and then a third career. He worked as a flying and sailing instructor and subsequently moved to Suffolk where he developed his interest in the secret wartime defence of Britain and started writing books. As he talks, he pays tribute to the courage of the auxiliers. They knew that if Britain was invaded their average life expectancy would be no more than a fortnight and yet they answered their country's call without hesitation.

John's fascination for the subject was sparked by his friendship with Herman Kindred who, with his brother Percy, owned the farm at Parham where the British Resistance Museum stands.

“I made friends with Herman because of his interest in the weather and my interest in the weather - his as a farmer and mine as a flier and sailor. I was a fellow of the Royal Meteorological Society and he had records on his farm, kept since the 1930s, of every day's weather.”

In the early 1990s a television company approached John and asked him to see if he could persuade Herman to talk about his war service but the Suffolk farmer flatly denied any war service.

John tried: “I said things like: 'You can tell me, Herman, because of my work background I'm used to handling sensitive material,' and he said: 'I don't know what you're talking about.'”

“So I said, 'Look if I get some authority from Whitehall will you tell me about it then?' and he said: 'I might' - a good Suffolk phrase that, 'I might'.”

As good as his word, John was able to put Herman in touch with a Whitehall official who reassured him it was all right to talk. “…and from that moment he couldn't be stopped. He'd been waiting for 50 years to tell somebody and I was lucky because he was such a good witness.”

Herman Kindred's secret was that he had been recruited to the GHQ Auxiliary Units - men whose ultimate task was, quite literally to “do or die”, John explains.

“Herman was approached, I think, by the commanding officer of the Home Guard detachment that he was in. He was told to go to Little Glemham village hall at a given time in a couple of days. He arrived there to find the place surrounded by armed guards.”

After being interviewed by three officers, Herman Kindred was told he was he was the “sort of chap they were looking for”.

Herman was selected as patrol leader and more men were recruited. The patrol had its Underground Operational Base (OB) at Stratford St Andrew and it was one of several Auxiliary Units in the area. Others included Framlingham, Leiston, Aldeburgh, Woodbridge and Ipswich.

“The place was crawling with them but they still didn't know of each other. Secrecy was initially paramount.

“They were then supplied with the underground operational base, a mass of firearms, very sophisticated explosives and booby trap devices and they loved it,” John smiles broadly.

“They roared about the countryside. They made a point of practising camouflage and night operations and they made a point of finding out when the police sergeant was going to have a point meeting with his police constable at night and posting themselves in secret so they could hear what they were saying.” “These guys loved it because it was better than being on 'bloody guard duty' with the Home Guard and turning up for parades and polishing buttons. Here they were in plain clothes, secretly and surreptitiously going round at night and blowing things up.”

It is hard to imagine that they wouldn't be rumbled but with air raids, army exercises and explosions to create tank traps and build pill boxes a few more wouldn't have been noticed, John says.

“In Suffolk there were about 35 such patrols; we're talking about 200 men.”

General HQ was established at Coleshill House on the Oxfordshire/Wiltshire border and, locally Auxiliary Unit Scout Sections were created. Mill House in Cransford was the Scout Section's Suffolk HQ, where a dozen men of the Suffolk Regiment, specially selected and trained were posted. They operated from Mill House until they were stood down in 1943, before D Day. John says: “Mill House acquired a spooky secrecy; an aura.” There were rumours locally that the men possessed superhuman powers.

The auxiliers were well armed. “They had a tommy gun to each patrol - which was usually given to the biggest man because it was so heavy - and American rifles and Churchill quickly instructed they should all be given revolvers during the days of critical firearms shortages. The most important thing they got, I think, was plastic explosive - PE - which had been developed by MI6 before the war and they got it in large quantities - before the army.”

It was deadly serious training in preparation for German occupation.

“It was, without any doubt, a life or death mission. A loose forecast of a fortnight of survival was what they worked to. They only had a fortnight's rations below decks in their OBs. They were expected to carry out an operation against the enemy every night and when they ran out of explosives they were to capture them from the enemy and use his.

“They were also authorised, whether directly or indirectly, to execute collaborators. This was also, of course, another major breach of international law and another good reason for keeping it quiet afterwards.”

As John talks, you are conscious that there may yet be much to discover about this underground army.

Next week: John Warwicker talks about the auxiliary units and the special duties section. Jill Monk of the special duties section and auxilier Donald Handscombe tell their stories

n Churchills Underground Army: A history of the Auxiliary Units in World War II, by John Warwicker is published in hardback Frontline Books, rrp �25

No suicide pills - but a gallon of rum

Jack Snowden asks if I'm sitting down before he reveals his age. He's 85 and he was in the Leiston Auxiliary Unit (pictured) - one of two men still alive, the other is Al Churchman. Jack is the tall young man pictured in the centre of the back row.

“I was the last man to join the unit and the youngest man to join.”

Like everyone in the patrol apart from Lt Denny (front centre) Jack worked at Garretts in Leiston in a reserved occupation.

It was the sergeant, childhood friend Baden Cracknell (seated front left) who asked if Jack would be prepared to join.

Jack Snowden says he hadn't known anything about the Auxiliary Unit - only that Baden didn't come to Home Guard parades.

“I said 'yes' straight away,” says Jack. “At 19-years-old you're prepared to die for your country.”

“We knew what we would have a very short life if the Germans ever came here.”

But, he added: “It was a bit more exciting than Sunday morning with the Home Guard.”

“We had the job of testing these Sten guns which were hopeless. We had to modify ours on Garrett's (machinery) to get them to fire a single shot otherwise they would go off on automatic on their own.”

The patrol's underground bunker (OB) was to take Jack by surprise.

“They took me on to Sizewell Common and they stood there talking to me and all of sudden out of the ground, on four little pillars, came about a yard square of turf and when it was lifted up about three feet off the ground on the steel pillars you could walk down a ladder underground.

“There were six little bunks and the smell of almond - the smell of the explosive. We didn't use much of it until the time came for us to stand down. We took the surplus of the explosive into the countryside and blew a lump out of a tree.”

He said the men were not supplied with suicide pills in case of capture “but we were given a gallon drum of rum to buoy our spirits up. We never drank it - we had to return it. I heard that some (other units) did manage to drink the rum but filled the cask up with tea.”

After the units were stood down in 1944 Jack “honestly never talked to anybody” about his service in the auxiliary units.

Training with live ammunition

Ivan Potter lived in Belstead village near Ipswich and was in a reserved occupation at the town's Ransome and Rapier factory. Like many of his colleagues he was in the Home Guard; a runner, working between two sections.

He was just 17 when he volunteered to join the Auxiliary Unit. The cover story was that they needed half a dozen young men to form a mobile squad.

“We went to Aldeburgh on a course for a fortnight. I think (the instructors) were commandos.

“We worked with live ammunition - I had a Browning automatic rifle. Being a real old country boy and born on a farm, we were all marksmen - even my mother. My father could take a penny off a gatepost with a catapult and a glass alley.

Ivan's OB was in Bentley Woods (“I can still find it with my eyes shut.”) The entrance was a steel cover over a shaft, camouflaged by a big tree stump. The exit was via a bank of holly bushes.

Ingenuity was the order of the day. Ivan made biscuit tin anti-tank bombs and describes how to fashion a nail bomb with a Bournville Cocoa tin, gun cotton, four-inch nails and a trip wire. “I had a bolt-action pistol I made from a no 1 shotgun. I sawed the barrel to 10 inches (and) put a pistol grip on it.”

And there was also the unlikely sounding carpet sweeper pill box destroyer.

A number of items from this home-made arsenal are on display at the Parham airfield museum.

He was undeterred by the short life expectancy of an auxilier in German-occupied Britain. “I was never frightened, me. I was a young idiot, wasn't I?” he laughs.

In 1943, Ivan Potter finally got the okay he was waiting for to leave Ransome Rapier and join the Royal Air Force where he trained to be a wireless operator. No one knew of his exploits in the auxiliary unit.

“As far as they knew we were just in the mobile unit. My dad was in the Home Guard and I went on parade with him and then I'd go off.

“Even my brothers didn't know - they got a shock when they found out!”

NEXT WEEK: Part two of the amazing story of the secret army.