BASE FOR HIGH-
LEVEL U.K. ESPIONAGE OPERATION
VISRAM HIGH SCHOOL A CENTRE FOR 'BLETCHLEY PARK' CODE BREAKERS
MOMBASA was once a major intelligence gathering outpost for the British Secret
Service during World War Two.
years' later details have emerged of an extraordinary 'code breaking' operation
mounted by a team of famous Bletchley Park cipher experts operating for eighteen
months out of the quiet confines of the Allidina Visram High School.
The disclosures are made in a remarkable new war history written by eminent
British intelligence expert Michael Smith and entitled 'The
Emperor's Codes - Bletchley Park and the Breaking of Japan's Secret Ciphers'.
From April 1942 through to August 1943 the Mombasa outpost named 'KILINDINI'
formed a vital link in the radio eavesdropping chain which blanketed the Indian
and Pacific oceans and reported to London, Washington, New Delhi, Melbourne and
While London read the now celebrated 'Enigma' codes from Berlin and
Washington perused Tokyo's 'Purple' cipher it was in Mombasa that code-breakers
helped interpret the all important Japanese JN4O code.
This later allowed the Allies to keep an hour-by-hour track of all movements
by the Imperial Japanese Navy.
So successful were subsequent breakthroughs that the Japanese merchant marine
suffered 90 per cent losses by August 1945 - victim to Allied submarines and
bombers alerted to their presence by this unique and deadly intelligence.
Many of Smith's fascinating revelations have been made possible only through
using recently 'declassified' British files, through privileged access to
Australian secret official histories, and interviews with an unprecedented
number of British, American and Australian code breakers.
While much of the book deals with operations from London, Washington, Colombo
in Ceylon (now Sri Lanka), Australia and Hawaii, the sections on Kenya, and
specifically Mombasa, are no less exciting.
Bletchley Park cipher experts had previously been monitoring Japanese signals
traffic from small units established at both Singapore and Colombo.
The collapse of Singapore and - in early 1942 - the Japanese raid on Ceylon,
and the growing concern that India itself might come under attack, persuaded the
British to withdraw their Far Eastern Fleet out of range of the all conquering
On April 25, 1942, the British Royal Navy's Admiral Somerville sailed for
Mombasa, taking the code breakers with him.
British woman intelligence officer Joan Sprinks recalled:
"We embarked in the AMC Alaunia, surrounded by many ships of the
"HMS Warspite, the flagship; the carriers HMS Indomitable
and HMS Formidable; the cruisers HMS Emerald and HMS Newcastle;
and many others.
"We arrived in Kilindini Harbour, Mombasa, on May 3, 1942 to an
accompanying welcome of wolf-whistles from HMS Royal Sovereign and were
quartered in a small hotel in Mombasa - the Lotus."
Their controller Paymaster Lieutenant-Commander Harry Shaw and his officers
selected an Indian boys' school at Allidina, overlooking the Indian Ocean about
a mile outside Mombasa.
The formalities of requisitioning the school and arranging for an armed guard
from the King's African Rifles took some time.
It was scarcely a promising start, made worse by poor radio reception
conditions and a basic lack of equipment.
"Our watchroom was constantly plagued by bats and masses of flying
insects, including praying mantises," she said.
"We cursed the Arab dhows that came in from the sea beating drums so
loud that we couldn't read signals at times."
WASHINGTON AND KILINDINI
For the British code breakers the transfer to Mombasa was at first very
difficult as signals frequently took up to a fortnight to be enciphered,
transmitted and deciphered
Efforts were made to provide a direct radio link between Washington and
Realising the latent potential of KILINDINI the British War Office soon
improved communications - provided through the R.A.F. in East Africa, who also
supplied special Typex (cypher/ coding) machines and offered more trained
Very soon after the KILINDINI codebreakers enjoyed their first major success
since leaving Colombo.
The Japanese Merchant Navy used its own special (JN25) codes or ciphers to
communicate with the Imperial Navy and to protect shipping movements.
Its replacement, JN4O, was believed to be a code super-enciphered with a
numerical additive in the same way as JN25.
But in September 1942 a textbook error by the Japanese gave the way in to
Mombasa-based code breakers John Maclnnes and Brian Townsend
By November 1942 the code-breakers were able to read all previous traffic and
be confident of breaking each message in real time, allowing enemy supplies to
be tracked and attacked at will by Allied submarines.
"This was the first time that any large body of non-coded naval Japanese
had become available," said Maclnnes.
Over the next fortnight, they broke two more systems.
The first was the previously impenetrable JN167, another merchant-shipping
The second was JN152, a simple transposition and substitution cipher used for
broadcasting navigation warnings.
There were three main code-breaking sections at KILINDINI:
• One working on JN40, which consisted of three code-breakers, a pensioner
clerk and two locally employed female clerks;
• A second working on the Fleet Auxillary System, JN11, a derivative of the
merchant-shipping code, JN40, which had taken over the most productive traffic;
• A third and very much larger section working on JN25 and led by the Dutch
naval officer Lieutenant-Commander Leo Brouwer and the veteran Royal Navy
codebreaker Lieutenant Commander George Curnock.
This had five code breakers assisted by three pensioner clerks and seventeen
The arrival of two Japanese-speaking Bletchley Park Intelligence officers Jon
Cohen and Hugh Denham coincided with further success for KILINDINI.
Outside of work, Allidina Visram School was a very relaxed place to be, Cohen
"Mombasa was lovely, a very nice climate.
"The Junior Officers' Mess was right on the sea front with the roar of
the sea hitting the rocks.
"We were members of the Mombasa Yacht Club which was allowed to sail
into the harbour.
"We made an effort to climb Kilimanjaro.
"Hugh did it and I dropped out 1,000 feet from the top.
"Then there was the beach.
"Nowadays, you see Mombasa as a tourist resort but in those days it was
"Once a week there was a classical music concert, records, of course, up
on the ramparts of Fort Jesus, the castle that the Portuguese had built.
"We all sat out on the tropical night listening to classical
By the end of March 1943 so much valuable information was being recovered
through KILINDINI that the British and Americans instituted a weekly U.S.
courier service between Washington and Mombasa.
As the war progressed with continuing Axis' setbacks many of the senior staff
from KILINDINI returned in August 1943 to London or moved closer to the Japanese
at their former base of operations in Colombo.
A shroud of 'Official Secrecy' was drawn over the KILINDINI operation and for
a further fifty years' few people outside Whitehall and the Pentagon were aware
of the significance of the sophisticated espionage establishment hosted at the
Allidina Visram School, Mombasa.
• 'The Emperor's Codes - Bletchley Park and the
Breaking of Japan's Secret Ciphers' is written by Michael Smith
and published in U.K. by the Bantam Press Limited.
Michael Smith is also author of the best-selling 'Station X - The Code
Breakers of Bletchley Park'.
He has previously written on intelligence matters for Britain's Daily
Telegraph, Financial Times and Sunday Times Newspapers.
AND THE ADMIRALS
Two other irrelevant anecdotes from Mombasa 1942:
(N.B. - THESE ANECDOTES ARE NOT FROM THE BOOK)
• The late George Spence was a Policeman and official 'Censor' when the
Eastern Fleet arrived in Kilindini.
He wrote of this period:
"There were more than 150 Royal naval vessels of all sizes and unusual
descriptions anchored deep into Port Reitz and around Port Tudor.
"At one time we had seven Admirals and two Generals, all with their
staff, on the Island.
"Mombasa was really 'Blood Pressure Corner'.
"There were high ranking officers everywhere you went and you marched
down the main road with your arm extended at a permanent salute".
McCREADY AND THE SERGEANT'S MESS
• Retired British soldier Gavin McCready was staying on holiday at Nyali
Beach Hotel last year and he told Coastweek:
"My last visit to Mombasa was in August 1942.
"Everyone was in the Army and we were all very conscious of our military
"I had just got my third stripe and was looking forward to my first
visit to the Sergeant's Mess.
"Well, in fact, it took me more than an hour to find it.
"Can you believe ... it was situated directly between the Hindu
Crematorium and the Infectious Diseases Hospital !"