Mike Leghorn wrote:

>I believe that one of the London halls had problems with traffic noise
>getting into the recordings. I think it was Kingsway Hall.

It was, but the noise came from underground trains - the Picadilly Line
to be precise - which ran right under KH.

Tony Duggan, England.
Mahler CD recordings survey is at:
http://www.musicweb.uk.net/Mahler/index.html