That DF procedure was being used as late at 1993 in anger. At EFTS Swinderby, it was our only approach aid - and we used it in anger frequently. For CAT A and B, the range outbound was 11NM, the minima 740' IIRC and although nothing like the ease of modern approaches, we got quite good at it because we flew it quite a lot. The students used to do a limited panel QGH as part of thier IFT - with about 40 hours total time. It was quite a challenge. When I wnet to CFS and had to fly my IRT on the Chippie using such a procedure after being 'dulled down' by hours flown on the Smiths MFS, I found it very difficult!