Much of Britain will come to a standstill at 11am to mark Armistice Day with the silence being observed at airports, railway stations, supermarkets and banks.

The Queen Mother will lay a cross in memory of fallen heroes

"We expect as many as 85% of the adult population - 50m people - to observe the silence this year," said a spokesman for the Royal British Legion.

The Queen Mother was attending the Field of Remembrance Service on the 81st anniversary of the First World War.

The Duke of Kent will accompany the 99-year-old great-grandmother to the service outside Westminster Abbey.

She will lay a cross in memory of Britain's war dead at the service, which she has missed only once since the Second World War.

Elsewhere in central London, on Horse Guards, the Last Post will be sounded by Lance Corporal Steven Perry of the Welsh Guards.

Silent respects

This is the fifth year in which the Legion has campaigned for the silence on 11 November and it has the backing of the three main political parties and organisations around the country.

Passengers travelling on BA flights will be asked to join cabin crew in a two-minute silence to mark the 11th hour on the 11th day of the 11th month.

Railtrack staff will observe the silence at all main line railway stations, with passengers invited to join in.

Many stations will be holding memorial services.

The British Legion has campaigned for two minutes silence

London Transport staff and passengers will mark the silence at Underground stations, though tubes cannot stop for safety reasons, while London Buses will, if practical, pull over to the side of the road.

Many companies will observe the silence, including Eurotunnel, Ford, Norwich Union, Shell UK, Vauxhall, McDonalds, Cadbury Schweppes, Jaguar, Nissan and Toshiba.

The start and finish of the silence will be announced at supermarket and superstore outlets.

Among those observing the silence will be Tesco, B&Q, Argos, John Lewis, Marks & Spencer, Waitrose, Sainsbury's, Asda, Safeway, the Post Office, Body Shop, Boots and Next.

Many radio and television stations will also fall silent, while admission to the Imperial War Museums in London and Duxford, Cambs, will be free on Thursday.

The National Memorial Arboretum in Staffordshire will hold a service of commemoration.

Ian Townsend, the Legion's secretary general, said: "People in all walks of life all over the country have welcomed this simple form of Remembrance.

"It introduces a poignant annual moment into their lives.