大象传媒

PROLOGUE
There must still be some of us left, now all well into our seventies or more, who can recall the night of Monday 27th/Tuesday 28th April 1942. The first night of the Norwich blitz. I was seven coming up eight years old at the time. Not surprisingly, the incident has left indelible memories that, even after more than sixty years, are still as horrific as on that night.

For me it started at around 11.30pm when I was awakened by the voice of my father, a WW1 veteran, loudly shouting, "Bombs, bombs!" The family was at that instant, in their beds, presumably sleeping. That is, mum and dad, two elder sisters and me. I was youngest and my dear mum must have grabbed me from bed and rapidly descended the stairs, entered the living room then took a restricted flying dive with me under our dining table. We were all just in time. The first wave of Luftwaffe aircraft were dropping their high explosive bombs, softening up the city for the later incendiary attack to take over with their devastating fiercly burning fires. Mum told me later that as she dived with me under the table, my head struck the table top, just above my right eye. In spite of this I recall the holocaust in our living room - I can see it now in slow motion just as I did then. Due to bomb blast red-hot ashes were sucked from the dying embers in the grate of the living room fire. I recall the singeing feeling on my bare legs. The glass in the French windows rapidly cracked before my eyes, starting with small circles in the centre and working outwards. Yet the still intact panes bowed towards us in the room but, amazingly to me, suddenly reversed their direction. Then amidst a turmoil of noise, doors and everything else reasonably moveable became wrenched by an invisible force to go flying out into the garden. Pieces of ceiling rained down and by now, more than likely, the blow on my head was taking effect. I may have run instinctively beside my mother to the underground shelter in our garden, but the next thing I knew was the family huddled together in our small, damp, underground dungeon. All were safe and alive - my mother openly gave thanks to God for our protection.

This was my initiation into 'man's inhumanity to man'. Sadly, it seems to be an ongoing theme.

INTRODUCTION
What I want to do is to be informative and entertaining, even though the subject is sombre and in some places unavoidably technical. It is my opinion that a reasonable explanation of the Norwich Baedeker raid has never been available. So called official reports may contain cover-up statements, war time security measures also meant that much of what transpired could not be given at the time. This is understandable, but even after over sixty years, records have never been set straight. The time is fast approaching when underlying truths will no longer matter to a later generation, and why Norwich was stripped of parts of her inheritance will be lost in unrecorded history.

Consider these points. Contrary to some official statements, no public aural air-raid siren sounded before the Luftwaffe first raid. The apparent selection of the Heigham area for more intensive bombing has never been explained. Norwich was known to be the target that night, because a Luftwaffe radio navigational beam, which they called their knickebein, had been detected and assessed before the air raid. A new anti-jamming modification the enemy incorporated into their beam was to work splendidly although British scientists, from intelligence reports, had long before warned our services of the newer technique to be used. The British countermeasure was poorly designed and certainly not tested for effectiveness in any way. Earlier countermeasures against enemy beams were highly successful. Quite often our defence services used knowledge of an enemy beam to guide our own defending fighter aircraft onto the incoming bomber stream. These successes may have engendered complacency. To our lasting regret, Norwich and her citizens suffered because of a relatively simple enemy ruse that fooled our services.

Over the years I have read many books about the second world war and the techniques employed by both sides to achieve adequate air navigation for accurate bombing. With my advanced age I cannot remember the names of many of these books nor of their authors, so a good deal of my explanations are drawn from memories of others' work. My current personal library, after years of travel, is sadly depleted of much useful reference work. However, where my statements are conjecture or reasonably intelligent projections of what is known, I will make a positive statement to this effect. Some may find my 'Beam' explanation a bit over the top, but try to stay with it. It may open your eyes as to how simple a well-designed navigation aid is to the user - in this case an aircraft pilot.

The Norwich Baedeker Raid of 1942 has many fascinating loose ends, it could be that some may find an answer here.

GETTING TECHNICAL
Let's start with the reason for no public air-raid siren being sounded. Please remember the enemy beam was already switched on, so for our defences, it was only a matter of waiting for the bombers to be plotted from radar reports as on their way. Over the years, I have talked to many fellow citizens who experienced that night of the first Baedeker raid, this has included young and old. Everyone is adamant, no warning siren was heard. Any filed report, which can be produced suggesting that we did have a warning siren, is highly suspect and probably represents a face saving document for some official.

The Norwich raid was both well planned and executed. Our British services were completely duped by the enemy's tactics. In a nutshell, the method was to send out a bomber force, in total about thirty aircraft. They were in waves of five or six, with good reason for this, as I will explain later. Their aircraft would fly northwards over the North Sea probably on a radio beam and when sufficiently north, level with the north Norfolk coast, they turned west and picked up their other beam. This second beam we had already detected - it was their intention - and it produced an aerial highway directly over central Norwich. Flight leaders ensured their bombers turned and were also tuned-in onto the second beam. These incoming enemy aircraft picked up their second beam over the general vicinity of around Sheringham and Cromer, on the north Norfolk coast. The clever part is that they now flew 'down' their beam to Norwich and not 'upwards' from the south as we anticipated. Can you now realise why any official report claiming the timely sounding of warning sirens must represent downright lies? We were taken completely by surprise. A simple enemy trick but highly effective.

In order to give a better idea of the problems our defence forces experienced, it will be useful for me to explain a bit later, in moderately technical terms, the basic principle used for a knickebein beam. For us, it took around two and a half years of warfare to realise how necessary radio navigational aids were for accurate bombing. In those early years, few experts on our side appreciated the poor accuracy of RAF bombing.

There was sometimes, even more often, a lack of understanding between aircrews and the RAF special personnel skilled in practical knowledge of radio techiques. Although ground staff, they were required to undertake flights in order to discover and evaluate enemy radio beams. However, these special personnel were not classified as aircrew and consequently carried relatively low rank. Aircraft, in which they did this work, were allocated at short notice and some flown by pilots apprehensive of being shot-down on a non-combative mission. One pilot, who felt slighted by low ranking 'erks' carrying out work he could do easily himself, made a superficial investigation claiming it was possible to fly and evaluate a beam accurately. Sadly, he crashed while conducting his one-man mission and died before any report could be made. These problems tend to be peculiar to the British system, which in those first years of the war was too rigid and hierarchal. A very flexible and co-operative organisation is required to deal with an unknown and changeable opposition.

Actually the navigational radio beam system used by the Luftwaffe was, in its basic form, quite well known and already used in civil aviation of that time. It was based on the 'Standard Blind Approach', by the mid-1930s a method used by many airlines at suitably equipped airports. The correct or commercially registered name of that system is the 'Lorenz Beam', not surprisingly, a German invention.

TRY THIS FOR SIZE
The Continentals were researching into what we now know as VHF long before the British. VHF will give only a short range of ground coverage, and in the 1930s this characteristic had no technical advantage for our home radio broadcasting services. The Lorenz beam blind approach system used VHF but it only required a relatively short range, at most around ten to fifteen miles. Luftwaffe research showed that at aircraft heights, rather than near the ground, much greater ranges were obtained, with some evidence that the beam did tend to curve with the earth's surface. They suggested that perhaps with greater transmitter power the Lorenz beam could be adapted to give a long-range aerial highway for accurate aircraft navigation. The answer obtained was a positive one, and by the late 1930s, the Luftwaffe tested and was satisfied with the system it then adopted. For very good technical reasons the Lorenz system has to use two beams, their having a marginal separation. The reason being that on VHF, one directional beam cannot be produced sufficiently narrow to be useful navigationally. These marginally separated beams have a critical overlap. This useful overlap can be made relatively narrow and with suitable transmitter power, its range could extend to over 200 miles. Another consideration is how the user, an aircraft pilot, can work the system to identify where to find the narrow central overlap and follow its direction. The answer it that the two separate beams, differently identified, are produced from the same transmitter but this is done sequentially. For example, the transmitter is connected to the left hand aerial as it sends a 'dot' signal. By very rapid automatic switching, the same transmitter is connected to the right hand aerial as it sends a 'dash' signal. The sequence between left and right, that is, dot and dash, alternates continuously. Spaces between dots are equal to the dash signal and vice-versa. A pilot in the outer area of the left hand beam listening on headphones will hear a series of slow dots. In the outer area of the right hand beam, he will hear fairly rapid dashes. If a pilot hears the dot signal and then flies towards his right, he soon finds that the dots become less distinct and then form a continuous tone as they merge with the dashes in the 'overlap' section of the two beams. The dashes fill completely the spaces between dots. Should he hear a series of dashes, he flies towards his left and the dashes will merge into the continuous tone of the 'equisignal' zone where the beams overlap. Obviously, a pilot flies along the equisignal zone, easily correcting any drift to either side of the required course. The system is user friendly and the technique is soon mastered. This principle, known as a split beam is the basis of the low power Lorenz blind approach technique. The Luftwaffe used this principle for what they called their 'knickbein' system. There were a number of variations of knickbein and they could include additional crossbeam stations to signal 'approaching target' and 'release bombs'. The transmitter and aerial system were housed on a large turntable that could be set-up accurately to give a navigational corridor extending well into enemy territory. Motorised mobile versions were also produced allowing rapid deployment at suitable sites.

The 'knickbein' used for the Norwich raid was more than likely situated at Calais, at that time enemy occupied territory. Evidence points to this location as being correct, as I will show. Over Norwich, the aerial highway had a width of about the distance between our City Hall and Castle Museum. It represented an identified swathe cut for accurate navigation and bombing. Together with intelligence information given to the aircrews, made it an easy matter to find and pinpoint most of what they hit with their bombs. Not a bad accuracy for 1942.

(more to come)

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