The original component part drawings were returned to BP from GCHQ.


mid 1996  

Research phase commenced


September 1996  

We made our first visit the Letchworth Garden City Heritage Museum and Archive.


11 November 1996  

A group of us visited the Science Museum Archive at Blythe House where we spent four useful hours researching the ex ICL archive material.


4th February 1997  

The first steel for the frame was cut but without any ceremony.


9 April 1997 We made a return visit to Blythe House where we took copies of data relating to standard BTM components as used in the late forties and early fifties. The BTM Standards Manuals was most informative. We found all the information we needed on relays and condensers (capacitors).
Last three months of 1997  

Letchworth Heritage Museum staged an exhibition entitled – Letchworth during WW II – We provided information from which a section relating to CANTAB was produced.


Sunday 7th September 1997  

The frame was delivered to Bletchley Park. This was the same day as the major welding took place.


Thursday, 11th September 1997 Formal delivery. We made a special event of the frame delivery at BP. This being partly to thank those who helped in the research & manufacture and partly for publicity purposes. The BP Historic Motor Transport Section brought out their Bedford 3 ton flat bed lorry and delivered the frame from one side of the Park to the entrance of the original Bombe Hut where the frame now resides. We had a very good turn out from those who are members of the trust with most of them being dressed in 1940s service uniforms. This together with the 1940s lorry set a very WW II scene. Incidentally, the original Bombes were transported from Letchworth and between sites using a Bedford lorry very similar to that used on the ‘delivery’ day.The then Chairman of the Bletchley Park Trust Sir Philip Duncombe welcomed the frame on site . We were very fortunate in having with us on the day many of those who had manufactured or maintained the Bombes during World War. This included representation from the RAF, Post Office and BTM. A buffet lunch was provided and the Press attended.

In addition to the Frame we have put up various displays and explanations in the Bombe Hut which all can see.

5th January 1998  

Briefing to Bletchley Park tour guides – Following this the Bombe Hut became part of the Standard BP tour


12th November 1998  

The two upper horizontal bars were removed from the Frame to be drilled and tapped (over 150 holes in one).


14th January 1999  

The two bars were replaced. To these were temporarily attached 26 plates at the top of the frame to prove fit and alignment.


31st March 1999  

Third and fourth horizontal bar fitted. Most Front and Rear Plates test fitted. Left Hand End Frame and horizontal thrust brackets added.


6th April 1999  

Second large pen plotter added to our facilities


22nd April 1999 Collected 34 castings. All these are made from very high-grade cast iron which machines almost like steel.
15th July 1999  

Last casting completed and ready for machining.


8th August 1999 Fit new Jack Frame – The gate that supports the relays on the inside and the Menu Jacks on the rear.
18th September 1999 Many of the Rebuild team meet WRNS who operated Bombes at their ‘Enigma’ reunion
27th September 1999  

First meeting with SMEE (Society of Model and Experimental Engineers)


9th February 2000  

Cableform team established and pilot work started.’Drilling and tapping’ team established


7th March 2000  

Unofficial Royal visit to Bletchley Park. Bombe Rebuild Project presented.


19 May 2000 Gathering of volunteers at Bletchley Park. Gearbox and Clutch Castings machined and on display
May/June 2000 Drawings and information provided to ‘Asylum’ for the production of ‘props’ Bombes.
16 June 2000  

Five ‘props’ Bombes delivered to Bletchley Park


24 May 2000 Photocopying exercise complete. Over 5000 documents copied and returned to Bletchley Park Archive
10 September 2000  

Final section of frame fitted. Frame now complete


March 2001  

Article on Bombe Project in Computer Weekly


4 April 2001  

Lecture given to IEE Essex Group


26 May 2001  

Gearbox, Clutch and DC Motor running off our own DC Power Supply


November 2001  

Article on Bombe appeared in IEE Review


16 November 2001  

Bombe appeared in new book – Letchworth Remembered 1939 – 1960


11 Dec 2001  

Lecture given at Bletchley Park to IEE Beds and Herts. group


January 2002  

Four Enigma test rig and demonstrator complete


19 March 2002  

Talk given to CCS North Group


April 2002  

Mechanical Phase complete. All moving parts turning under DC power


20 May 2002  

Indicator Unit refurbish complete


5 June 2002  

Talk given to Surrey IEE


17 June 2002  

Bombe and Spirella prints collected from Letchworth Heritage Museum


August 2002  

Material for electrical parts being acquired. High volume CNC parts ordered.


10 September 2002  

Computer Conservation Society visit to BP. Lectures and Presentations.


18 September 2002  

First Prototype Drum Assembled


4 October 2002  

Volume plastic moulding started at Nortel, Harlow


10 October 2002  

Bombe talk given to Old Cedarians Association (my old grammar school)


22 November 2002  

Bombe talk given to Wilmslow Guild (Town where Alan Turing died)


27 November 2002  

First Cableforms being fitted


20 February 2003  

Bombe talk given to Hertfordshire Engineers Luncheon Club


9 April 2003  

British Computer Society Plaque Presentation event; BCS now a major supporter


11 June 2003  

Move from Bombe Hut (Hut 11) to Block.H.


June 2003  

Menu plug manufacture started


20 June 2003  

Covers discussed with  gentleman who worked on them in W.W.II. No drawings available. New drawn from this help and photographs


16 July 2003  

Large number of solder tags made commercially on CNC punch


30 July 2003  

Start of relay gate assembly


20 August 2003  

Assemble and fit Stop & Cancel Assembly


1 October 2003  

Drum brush grinding jig finalised


6 October 2003  

Pattern for brass lubrication junctions made and delivered to foundry


13 November 2003  

Gave lecture at BP – British Bombes


26 November 2003  

American Lady presented original commutator to BP. Bombe appeared on ‘Look East’ Television


13 January 2004  

First 14 Letchworth Enigmas fitted to frame


2 February 2004  

Lubrication pipes being manufactured


17 February 2004  

Lubrication manifolds complete


7 April 2004  

29 Letchworth Enigmas now fitted


15 April 2004  

Start fitting parts to the Sense Relay Shelves


19 May 2004  

Stop & Cancel Unit assembled and tested


20 May 2004  

Checking Machine woodwork complete


3 June 2004  

First 30 Drums completed


20 June 2004  

First Reflector (Uncle Walter) panel complete


2 July 2004  

New unpainted covers arrived at BP


30 July 2004  

Fitted covers


9 September 2004  

Purchased our own Project CNC model makers mill


16 September 2004  

First major assembly of Checking Machine


8 October 2004  

Move from Block H at Bletchley Park to Block B.

15 October 2004  

Lord Sainsbury given a demonstration of progress to date


1 November 2004  

Gave talk to Shuttleworth Aircraft Supporters Group (AEG)


7 January 2005  

First part made on our Project CNC mill


17 February 2005  

Lubrication System completed


4 March 2005  

Started fitting running relays and Cam Unit


12 April 2005  

Painted Covers refitted


26 May 2005  

Started making special wire-wound resistors


27 June 2005  

Fitting Stop and Cancel Relays


16 August 2005  

More Checking Machine Assembly


6 September 2005  

Checking Machine Lamp Panel complete


15 September 2005  

Checking Machine Keys fitted


14 October 2005  

Gave talk at ICL Double Majority Association AGM


4 November 2005  

First 30 Drum Bezels completed on CNC mill


24 November 2005  

Started making a special relay tester for High Speed Siemens Relays


8 February 2006  

Sense Relay trays being assembled with new High Speed Siemens relays


13 April 2006  

All sense Relay trays equipped and fitted


18 April 2006  

Construction complete except for full set of drums


24 May 2006  

Bombe commissioning commenced.


12 June 2006  

Decision to modify BP Typex to act as an Enigma machine


15 August 2006  

Checking Machine complete other than last 3 drums


29 August 2006  

Typex Machine now working as an Enigma Machine. Also first Static menu working


6 Sept 2006  

Press day. Bombe seen on National Television and National News papers etc.


24 Sept 2006  

Enigma Reunion. WRNS and other veterans see all our complete machines.


circa May 2007  

Machine now stopping reasonably reliably on a genuine W.W.II menu


12 July 2007  

Part of the British Computer Society 50th anniversary celebrations. Machine demonstrated reliably to over 100 guests


17 July 2007  

Official ‘Switch On’ at Bletchley Park by His Royal Highness the Duke of Kent. Machine now fully reliable and predictable.

See photo

See also at Computer Conservation Society WEB site


circa August 2007 Double Input working. This requires two sets of Sense Relays operating before a ‘stop’ is detected.
23 September 2007  

WRNS ‘Switch On’. Most WRNS who had worked on the Bombes during WWII were not able to attend the ‘Royal Switch On’. Therefore a special event was arranged on the Sunday of the Enigma Reunion Weekend.

See photos

29 September 2007  

An example of Umkehrwalze ‘D’ was wired onto a reflector plugboard and a representative menu then run successfully. Typex configured as an Enigma also wired to the same configuration.


A continuation of the diary can be found in a slide show at

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