There's nothing of significance in it as far as I can see.
Checking the AIP chart, 27L has about 450M from the threshold to the road (it doesn't show the fence), 27R has about 10M less (actually on the southern edge it has slightly more, as the road in the 27R undershoot is perpendicular, in the 27L it is diagonal, shortening the distance). Don't forget that 27R has nearly twice the length of unusable tarmac before the threshold compared to 27L, making visual comparisons difficult.
This plane would have been making a fully automatic approach with the handling pilot ready to take over if it went pear shape.
The aircraft would have been on autopilot for the approach, but it's very unlikely it would have made an autoland, unless it was for training purposes, as the weather was certainly above visual minima. We usually hear the autopilot being disconnected as the crew read back "Cleared to land" - although on a nice day I have heard it much earlier than that. LHR also wouldn't have been "safeguarded" unless ATC had been given prior notification that the crew wanted an autoland, which means that there could have been work parties, vehicles or other obstructions in the critical area, making the signal unsuitable, or at least not guaranteed, for an autoland.