A minor benefit of the blast-wave was that some of the innumerable fires started a few seconds earlier were blown out and did not rekindle. This was small mercy, however, compared with the even larger number of fires which were effectively fanned by the outward moving winds.
Birmingham airport, twelve kilometres from Winson Green, suffered relatively light damage, but wind speeds at the airport were of the order of 160 kilometres per hour and many aircraft lost wings and tailplanes or were turned on their sides by the blast-wave. Outside this range the effects of blast fell off rapidly, damage to buildings being confined to broken windows and shifted roof tiles.
The blast-wave had rolled outwards from the centre at something like the speed of sound, arriving at Birmingham airport approximately thirty seconds after the detonation of the weapon. Even at this point the roar of the explosion was stupendous, lasting for ten to fifteen seconds. The same roar was to be heard in London, approximately eight minutes later, as a rumbling, roaring noise from the direction in which the blinding flash of the fireball had been seen eight minutes earlier. Those in London with any knowledge of nuclear weapons were in no doubt as to what had happened.
Within one minute the stupendous activity of immediate damage from the detonation had ceased. The enormous mushroom cloud above the totally devastated centre of Birmingham had risen to a height of fifteen kilometres and had spread across a diameter of approximately twenty kilometres. It cast its shadow over a scene of extraordinary destruction, where everything was still except for the occasional crash of falling masonry and the crackle of multitudinous fires. Within a radius of five kilometres of Winson Green everything seemed to be on fire. Outside this area, to a range of about eight kilometres, hardly any building, or what survived of it, seemed to be free of a fire of some sort. Fires occurred less frequently outside this range though there were buildings on fire at ranges of up to fifteen kilometres. There were fires in towns as far away as Wolverhampton, Stourbridge, Halesowen, Solihull, Sutton Coldfield, Walsall and Brownhills.
The devastation within the centre of Birmingham was so intense that the road system had ceased to have any meaning, most roads having totally disappeared beneath the rubble of the buildings once standing along them. Outside this area, and to a range of five or six kilometres, all roads were totally blocked by fallen masonry. The only means of movement around the area was provided by the M5 and M6 motorways which encircle the centre of Birmingham. These roads, being wide and not hemmed in by buildings, remained relatively free of obstruction. The bridges along them had also survived remarkably well. Outside the motorway route the degree of devastation began to tail off, although most buildings still appeared to be unusable. Almost all roads were so littered with rubble that no immediate movement of vehicles was possible. The centres of Dudley, Walsall, Sutton Coldfield and Halesowen were impassable, though in these towns the outline of the road system was still visible and the overall extent of the damage, though still enormous, was considerably less than in the centre of Birmingham. Fires were prolific, particularly in commercial premises in high streets and commercial centres, holding large stocks of inflammable materials. In many places the gas distribution network had been broken and fires were being fed by escaping gas.
The fires which were now alight across a circle with a radius of approximately fifteen kilometres centred on Winson Green were beginning everywhere to take hold. In particular the fires amongst the devastated remains of the centre of Birmingham were beginning to burn fiercely. As the flames rose higher into the sky air was drawn in from outside, with the result that winds began to blow inwards towards the flames. This further fanned the conflagration so that, within twenty minutes of the original detonation, an area of approximately thirty square kilometres in the centre of Birmingham was totally engulfed in a fire-storm. The flames and smoke rose hundreds of metres into the sky as the in-rush of air fed and fanned the fires. The in-blowing air prevented fires moving outwards but everything within the fire-storm area was now engulfed by it. Outside the area of the fire-storm thousands of other fires were burning furiously. In peacetime many of these would have been regarded as serious fires requiring the attentions of a significant proportion of the fire-fighting effort available locally. As it was there were so many such fires burning at once over a total area of about 600 square kilometres that conventional fire-fighting equipment could have little or no effect upon them.