How worried was Britain about invasion 1940-41?

Transcript
Information to be broadcast by the BBC if German forces landed in London

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S E C R E T.

INSTRUCTIONS TO BE GIVEN TO THE PUBLIC THROUGH THE
BBC ON "ACTION STATIONS".

This is a message for everyone who lives or works in London or may find himself there in the near future. By London is meant the Metropolitan Police District or the City of London.

If invasion comes, London itself might be attacked, perhaps quite suddenly, by air-borne troops landing on open spaces in or near London. If this should happen it might be necessary for a short time to stop all vehicles over a wide area in order that the Military Command, after getting some idea of how the attack was likely to develop, might have the roads clear to deal with it. The signal for this traffic stop will be the sirens, which will sound their steady note for five minutes, instead of for one minute as they do for the "All Clear". On this signal all vehicles must stop, except civil defence and public utility vehicles on vitally urgent service. These must be ready to obey whatever orders the police give.

If you hear this signal when you are driving a vehicle you must drive up on to the pavement, or, if there is no pavement, to the edge of the road, and wait until the police tell you what to do. Stay with your car or as near as you can with safety. Do not immobilize it unless told to do so.

Buses and trains will stop as soon as they get to the nearest collecting point, where they will await orders. Trains will go on running.

Pedestrians and cyclists need not stop, but should go on to their destinations. Passengers by train who have reached their stations and passengers by bus whose buses have stopped should also go on to their destinations. If they cannot do this, they should ask permission to wait in a house or other building nearby -and in any case they should not wait in crowds at stations or bus stops.

If you are at home or at work, stay there; obey the "Stand firm" orders.

The traffic stop is not likely to last long. As soon as the Military Command have sized up the situation and decided what area they want to keep cleared, traffic will be released everywhere else. The signal will be cancelled by instructions given over the wireless and by the police in person or through loudspeakers.