On 5 Feb, 00:38, "SimonD" wrote:
I was standing half way along the southbound Victoria Line platform at
Kings Cross, when I happened to look up through the vents in the
roof. Through them, I could see daylight, coming in through what
appears to be another tunnel running more or less parallel to the
Victoria Line.

I've used this platform many times, but have never noticed this other
tunnel before. Is it new (in some way connected with the northern
ticket hall works), or has it always been there? If so, has something
been done to allow light into this tunnel?

Or, has it always been like this, and I've never noticed.

I think the tunnel has always been there - the shafts leading into the
Victoria line platform tunnel are integrated with and of the same
design as the original panelling. I noticed that they are artificially
illuminated at night at least - I haven't seen during the day. From
the design of the grilles on the Victoria line tunnel roof, I think
they are part of the ventilation system for the station. I'm not sure
if they are being modified or incorporated into the works connected
with the Northern Ticket Hall though.