The mean heights of production of muons of various momenta in large air showers have been determined from measurements made with the Haverah Park magnet spectrograph of the lateral and angular scatter of muons from the shower core and the geomagnetic distortion of the muon charge ratio at various points in the shower front. The heights of origin of muons of momentum pGeV/c recorded at distances of r km from the core are given by: H(p,r)=H0+ alpha lgp+r/ beta where H0=1.68+or-0.15 km, alpha =1.74+or-0.20 km, beta =0.263+or-0.033.