Strange lights over London Underground tunnel near King's Cross (Dec 14th, late evening)

This happened a few weeks back and I've been debating whether to post it, but figured this is the place. I work nights at King's Cross station (in operations), and on December 14th around 11:45 PM, three of us saw something odd in one of the maintenance tunnels.

We were doing a routine inspection walk through the tunnels that run parallel to the main lines. It was me, Derek (been there 20 years), and Samir. Visibility was standard - bit of moisture in the air, our torches working fine. Suddenly, about 100 meters ahead, we saw a soft glow - not a torch, not emergency lighting, something different. Pale blue-green, maybe 1.5 meters off the ground, and it was moving.

Derek called it in to control room immediately. The glow moved deeper into the tunnel, away from us, and disappeared. Control room checked all other personnel and systems - nobody else was down there, no maintenance work scheduled. They found nothing.

I'm not saying it was anything paranormal necessarily, but it wasn't anything explained either. Has anyone else had experiences on the London Underground? Those tunnels are OLD and there's a lot of history down there.

Bioluminescence from fungi or bacteria? The London Underground is damp and has plenty of decay. I know it sounds boring compared to the excitement of paranormal activity, but it's plausible.

I used to work for TfL and there's definitely weird stuff in those tunnels. Mostly explainable (old wiring, gas leaks producing visual distortions, etc.) but this one's interesting because you've got multiple witnesses and control room confirmation. That's more solid than most reports.

pale blue-green, maybe 1.5 meters off the ground

That's the height of what people describe in other underground anomaly reports - the London reports from the 1950s-60s mentioned similar lights. Probably coincidence but worth noting. Any chance of getting the station logs from that night?

Cheers for posting this. King's Cross has some wild history - people dying on those platforms, bodies left in tunnels during the war. Not trying to be spooky but the Underground absolutely has claims attached to it. Would love to hear if anything else happens.