"Troy Steadman" wrote in message
news:9965a7ddbe9c818b6bb25a4b0207a05c.125090@mygat e.mailgate.org...

Could it be the Fleet River? I cannot find a link for its course at that
point but it is certainly very close and travels N-S.

Thanks for that, Roy (and all the others). However, I don't think it can be
correct as it would mean that the Fleet River was at street level and I
don't believe it was/is. In fact, it can't be, because it passes underneath
the Regents Canal. I went to a talk on the workings involved with all the
alterations at Kings Cross/St Pancras and apparently the Fleet River has
been diverted through part of one of the old tunnels which used to connect
the widened lines with the suburban lines going north. I believe it used to
run down the present alignment of York Way. It couldn't have been the
westernmost one as that was being used by Thameslink until very recently and
would be close to the area in question but below ground. The other two
runnels came up either side of Kings Cross and I believe they used to carry
the Moorgate trains which now go via Finsbury Park/Drayton Park.
I only wish you had been right !!
Cheerz,
Baz