It was in the early stages of the Second World War, when the paint was barely dry on the five-year-old tunnel, that it caught the attention of those responsible for planning infrastructure in the wartime economy. Top secret correspondence was sent from the wartime ministries of Supply and War to the Ministry of Transport and the Liverpool City Engineer.
There was clearly potential in two miles of underground tunnel, mostly 13.5m (44ft) in diameter, though there was little consensus on what exactly they might like to do with it.
All the same, one William Chamberlain from the MoT convened with the City Engineer and sent back a (top secret) list of possible ways in which it could be commandeered. He was very fast to point out that Liverpool was the busiest port in the empire, and that most of its substantial cross-river traffic went through the tunnel, many of the old steamer ferries having been decommissioned shortly after the new road opened.
The possibilities therefore looked at how to keep it partially open, perhaps only permitting goods vehicles necessary to the war effort. One idea was to partition it vertically, leaving two traffic lanes open and using the other two for storage, giving a space more than two miles long and 22 feet wide. The more realistic proposal was to close the narrower branch tunnels to New Quay and Rendel Street, or to close the main lines between the branch junctions and the surface, leaving the narrow branches as the only ways in and out.
The principal requirement was somewhere to store aircraft. In 1940, American aircraft were being transported to Britain by sea and unloaded in Liverpool, and it was anticipated that a surplus could eventually be built up. The planes were to be dismantled and discreetly stored underground somewhere.
Slightly more worrying was the proposal to use 'Central Avenue', the space beneath the main roadway intended for trams, to store oil. Various ideas were put forward for this, the most frightening of which was simply to pump the oil straight in until it was full. The City Engineer was asked to investigate the viability of cutting holes in the road surface to make accesses to the lower level for the storage of crates or rubber. It was even proposed that the dock branch at the Liverpool end be turned into one long, thin munitions factory for Vickers staff to work without fear of air raids.
Investigations into all sorts of applications were carried out and meetings held for quite some time. In the end, however, it was decided not to put the tunnel to any special use. Part of this was down to practicality: storing aeroplanes in a tunnel is not an easy thing to do; if oil were pumped in it would be very difficult to get out again. The point was raised that if the Liverpool Dock Spur were turned into a factory, there would be advantages to a linear production line of about half a mile in length, but if there was any sort of fire or emergency (always a possibility around explosives) there would be no safe escape route for the hundreds of staff down there.
Furthermore, it was feared that if certain branches were closed and put to different uses, then one single well-placed bomb could put the whole tunnel out of use by destroying one of the portals. The docks at Liverpool — the largest in the Empire — were running at full capacity to support the demands of the war and the tunnel was vital to their operation. There was also the important consideration that the Queensway was being used as an unofficial bomb shelter. Five minutes of walking into the tunnel could put you into a much more secure environment than any of Liverpool's official bomb shelters, and after a time the authorities gave up and permitted this use.
It's something of an anticlimax, then, to find that no particular use was found for the Queensway during the war. But it's incredible to think what could have happened under the Mersey if it hadn't proven so difficult to protect.
It seems that, since the Rendel Street branch was closed in the mid-1960s, alternative uses for this section of tunnel have been found once more. Paul Thomas writes:
"The last time I remember the Dock Entrance being used was for a Fire Brigade exercise with the unlikely scenario of a lorry carrying a container of nuclear material having crashed there."