Thank you Laurent. There is an online account of the raid (
http://blitzincidents.blogspot.co.uk/2014/01/ - one needs to scroll down to
High Holborn - the morning of 8 October 1940). Although this quotes a number of sources (ie Chris Goss's
Luftwaffe Fighter-Bombers over Britain) the author has cherry-picked to construct a generalised account rather than something specific to the 8 October.
Basically I'm writing a brief biography of one of the casualties, Joan Ellen Hill, a clerk at the Met Office HQ in Whitehall and, if possible, I'd like to add more specific detail than is given by the above link.
Brian