Ditto this. The only time I can recall using 2L at LHR has been on a remote (or intl stand for domestic flight) stand, or on occasion at NCL when the airbridge hasn't been working - they pull the plane right forward so the steps won't fit by 1L
Interestingly, the US carriers seem to use 2L as a matter of course on the 757's, even with an airbridge attached.