Here are some other sites which may be of interest:

Comer Homes ComerHomes.co.uk - the new owners of the site
Nortel Nortel.com - the company (previously known as Nortel Networks) that sold the site.
Nortel Pensions NortelPensions.com - went live on 3rd January 2003 - useful information for pensioners and those maybe not quite there yet... STC was subsumed into Northern Telecom (later known as Nortel) in 1991, so people looking for STC pensions information will also find this link useful.

STC Harlow

Derelict Places (and more here at Lost Places) thanks to Roger Millichamp for sharing

STC Monkstown

Davey Anderson's blog gathering photos and history of STC's Monkstown location

STL QCC

The Harlow STL Chapter of the Nortel Networks Quarter Century Club

Wikipedia - STC
Wikipedia - Nortel

Some interesting potted histories of the companies. One should always bear in mind to view what one reads on the Web with a healthy scepticism, of course. Including this site ;-)
EBRA EastBar.net (East Barnet, geddit??) - The East Barnet Residents' Association takes a keen interest in local planning and policing issues.
Friern Barnet & District Local History Society The President, John Donovan, lived in Friern Barnet between 1966 and 1995 and worked at STC. He became concerned that nothing was being done to record and preserve the history of the area and, before long, there would be no-one left who remembered it...
Light Straw A website celebrating obsolete technologies, dusty old papers, reminiscences of the not so distant past... Of interest to those of us who remember Strowger, Crossbar, TXE4...
RAF Hendon There's a mention of STC New Southgate on the RAF Hendon website
TXE Engineering Society

Aim & Objects:
•To further the acquaintance of all Telecoms engineers
•To broadcast the virtues of the TXE & ESR1 design philosophies
•To further these aims by meetings P’ Ups, and other activities

Disused Stations

For information about the cemetery railway station on what was to become the STC New Southgate site

If you know of other links, please contact Rob White