Southampton (SOU) has a 37M wide runway but has had many B757 movements. Something of an anomaly as in accordance with CAP 168/ICAO Annex 14 this runway is a Code 3 but the B757 is a Code 4 aircraft, something that has been frequently commented on by the CAA but apparently not within their power to prevent.
Can only assume that the operating airlines have satisfied themselves via a risk assessment that the proximity of the engines to the edge of the paved surface is tolerably safe.