27/28 September 1940: The London Underground on this day 75 years ago

Twenty-first day/night of the London Blitz.

"The enemy was very much more active during the day than usual. Three attacks were made on LONDON and some damage was done to the Southern Railway."^[1]

On Friday 27th September 1940, previously suspended services between Northfield and Hounslow resumed at 08:52, and between Turnham Green and Richmond at 14:00.^[2]

At 21:47, a 250kg High Explosive (HE) bomb hit the road of Haverstock Hill 100 yards (91 metres) north-west of Chalk Farm Northern line station, 32 feet (10 metres) directly above the southbound running tunnel.^[3][4]


It was later reported:

"Exceptionally few windows were broken and the clock was not even stopped in the station; the men in the control room experienced a heavy thus and the structure trembled, but they did not notice this particular bomb more than others in the neighbourhood."^[5]

Segments were cracked in segments of thirteen rings of the northbound tunnel, while the southbound suffered fractures in twenty-three rings, with a 20 x 30 inch (50 x 70 cm) hole blown through one segment at waist height above the rail level.^[5] Services were initially suspended completely between Camden Town and Golders Green stations, but the damage in the northbound tunnel was judged to be of a level that would still allow the running of a full-length shuttle train service through it between Camden Town and Hampstead.^[5][6] The following day a bus service was instituted between Chalk Farm and Belsize park, with the stations only open for booking purposes.^[7]

After visiting the site on the 28th, Lieutenant-Colonel AHL Mount of the Ministry of Transport reported:

"All the engineers concerned were of the opinion that had this damage taken place under the River [Thames], water would have poured into the Tube at many places, and the Inspecting Officers agree."^[5]

At the time the practice was to close the floodgates either end of all the tunnels running under the Thames, between both Charing Cross (now Embankment) and Waterloo, and London Bridge and Bank, but despite the near catastrophic experience at the former on the 9/10 September (see here), it had been strongly suggested that the tunnels at the latter, being much deeper below the river bed, were less at risk, and so could be kept open. Mount was emphatically opposed to this, and considered that this new incident - coupled with the damage at Mornington Crescent on the 8/9 September (see here) - was clear evidence that the existing cautious working practices were correct:

"It is clear that the additional depth of the tubes [at London Bridge] does not justify differentiation from the procedure agreed for the Charing Cross and Waterloo floodgates. The Inspecting Officers are not carrying out their normal functions in this respect. They are normally the Minister's technical advisers on all railway matters; but backed by their knowledge and experience of the last two years, they are in a better position than anyone else in this Ministry to advice the Minister upon the risks which should justifiably be taken in a matter of policy of this kind, and they have no-one upon whom their responsibility can devolve.

It is easy to be wise after the event and say that a risk might safely have been taken after no bombs had fallen during any particular Red Warning; but this Ministry will be hard put to it to find an excuse if, after having spent many thousands of pounds towards making the Tube system safe for transport purposes, the floodgates which have been provided at London Bridge are not used, and the Tube system is flooded in consequence and put out of action for the rest of the war, not only for transport, but even as refuges, together with the almost inevitable loss of many thousands of lives."^[5]

Damaged segments in the southbound tunnel were extensively replaced, whilst those in the northbound tunnel were merely reinforced, pending full replacement later (see plan below). Full services resumed on 7 October 1940.^[5][8][9]


At 23:25 services between Uxbridge and Rusilip on the joint Metropolitan/Piccadilly line were suspended due to a reported HE on the track; normal working resumed at 00:20.^[6]

Stockwell station on the Northern line was closed at 05:45 on the 28th due to a Delayed Action bomb in front of the station.^[6] Station re-opened by 18:00.<sup>[7]

[1]</sup> Ministry of Home Security, Key Points Intelligence Directorate: Reports and Papers, Daily Reports - September 1940: Damage Appreciation 26-28/09/40, page 1 [Kew: National Archives, reference HO 201/2]
^[2] Railway Executive Committee: Files: Form RWD1, 06:00-18:00 27/09/40, sheet 1 [Kew: National Archives, reference AN 2/1104]
^[3] Railway Executive Committee: Files: Form D2, 18:00 27/09/40 to 06:00 28/09/40, sheet 3 [Kew: National Archives, reference AN 2/1104]
^[4] Ministry of Home Security, Research and Experiments Department: Registered Papers: Damage to underground railways, drawing 14C [Kew: National Archives, reference HO 192/8]
^[5] Ministry of Transport and successors, Railway Divisions: Correspondence and Papers, Air Raid Damage - Underground Railways, 1941-1942 [Kew: National Archives, reference MT 6/2766]
^[6] Railway Executive Committee: Files: Form RWD2, 18:00 25/09/40 to 06:00 26/09/40, sheet 1 [Kew: National Archives, reference AN 2/1104]
^[7] Railway Executive Committee: Files: Form RWD1, 06:00-18:00 28/09/40, sheet 1 [Kew: National Archives, reference AN 2/1104]
^[8] Ministry of Home Security, Air Raid Precautions (ARP GEN) Registered files: AIR RAIDS, Incident Reports, Tube incidents statistics [Kew: National Archives, reference HO 186/2419]
^[9] Ministry of Home Security, Research and Experiments Department: Notes: Notes on damage to railway tunnels by high explosive weapons Section 1, Tube railways. 26 March 1942. Author, Dr. EWJ Phillips [Kew: National Archives, reference HO 196/11]

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