The Northern Line tunnel to the south of platform 1 at Liverpool Central station. I don't know what the CSR 39 sign is referring to, but my guess is that it is related to the Cab Secure Radio system. 
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Photo by <a href="mailto:cmckenna@sucs.org?subject=rail-photo at railfaneurope.net">Chris McKenna</a>07/04/2006.<br>
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