Never heard of the Porka ... YLSNED
DF could be a good get-you-down provided that the antenna was in a decent position relative to the runway. However, the brick blockhouse was usually well offset to the side, so a straight homing to the antenna would put you on the grass. I did try, in my intensive DF days at Strubby, of doing an inbound homing on a very slightly offset heading, and then kicking off the angle when the pilot called [on request] Outer Marker which was on the coast a bit south of Mablethorpe. In theory that had him roughly on the centreline with 3.5 miles to run. Safe enough over the flatlands of the Lincolnshire coast, but far from an exact science!
We did a lot of time-related procedures back then, which is why the Approach Controller was always equipped with a pair of HM Stopwatches - as indeed was Local where a DF display was fitted.