Since then, I always transit through Heathrow. It's a logistical nightmare with all those buses, but they've never coerced me to go through a scanner. Those biometric checkpoints, on the other hand...
[Note: This was with Dutch staff for British Airways; not sure if that's relevant.]
From Heathrow's security FAQ page (http://www.heathrow.com/more/help-with-this-website/faqs/sec...):
The only alternative that can be offered to a scanner is a private search which allows for a more extensive hand-search than usual. Passengers will be escorted to a different location in the airport from the main search area (eg a private search room). The private search may involve the loosening and/or removal of clothing. A person undergoing a private search may ask to be accompanied by a witness.
This alternative screening method will take significantly more time than passing through a security scanner.