Helicopters will fly members of the elite Special Forces regiment to scenes of attacks at a moment’s notice.
If terrorists are at large, the heavily-armed soldiers will be sent in to trap and eliminate them on the direct order of Home Secretary Theresa May.
News of the unit, which has been secretly rehearsing a variety of terror scenarios for months, emerges after last week’s atrocities in Brussels.
The soldiers include men and women from ethic and Asian backgrounds who mingle in crowds looking for anyone acting suspiciously
The bombings led to more than 30 deaths and scores of injuries after terorrists detonated suicide bombs at the city’s Zaventem airport and Maelbeek Metro station.
Crucially the mobile unit, dubbed Blue Thunder because it uses unmarked blue Dauphin helicopters, will provide a capacity to respond to incidents outside of London, in regional towns and cities.
Working under the direct command of counter terror police, the force of 70 SAS will operate alongside seven police liaison officers from three key airfields, as well as two provincial airports.
In January, the Sunday Express revealed how the RAF and intelligence services at GCHQ had foiled a terror plot hatched by jihadi commercial airline pilots which would have targeted Bath, Brighton and Ipswich as well