Great St Mary's has a public address system with microphones, loudspeakers and inductive loop, so that
The loudspeakers are set on stalks on the pillars of the church building, silhoutted and set at an angle constrasting with the general lines of the architecture, so that those not paying attention to the sound are able to see that care is being taken to address their listening comfort at no effort to themselves. There is also a symbolic value in this, as there is in many parts of such an ancient church building: that the church of today, in order to be relevant to the society in which it lives and witnesses, is leaning at an angle and visibly attached to its ancient foundations by a thin stalk.
The provision of a sound system also helps the congregation to avoid the awkwardness of occupying the front pews (with its attendant risk of the suspicion of enthusiasm) while saving the celebrant and readers from having to project their voices (which again could be taken for enthusiasm, leading to confusion with, for example, the early methodists; we've had enough of our members burnt at the stake in the past, and don't want to stir the waters now).