Sources
- Initial planning and early proposals for a bridge across the Mersey: National Archives MT 39/123.
- Opening ceremony and details of tunnel at opening: National Archives RAIL 474/255.
- Proposals for wartime use of the tunnel: National Archives MT 39/488.
- Flyovers at Liverpool end of the tunnel, proposals and construction: National Archives MT 118/215.
- Flyovers and traffic control at Birkenhead end of the tunnel, proposals, construction and operational difficulty: National Archives MT 118/261.
- Birkenhead traffic control system opening ceremony and commemorative booklet: National Archives MT 118/261.
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