Land Rover Repair: Discovery 1 ABS issue, wheel speeds, forward momentum

Question
I have a '98 Disco that will intermittently lose braking power. The issue is intermittent. It happens more often when the temp outside is cold. It can happen more than once in successive braking attempts, or happen only once. It can go days between occurrences. The symptom is a hard pedal and little effect to forward momentum. The ABS light works fine and does not stay lit or act up at any time. Seat of the pants tells me it's the ABS pump intervening, but as it happens in a straight line on level tarmac, differing wheel speeds doesn't appear to be a factor. Could this be a sticking ABS Pump relay, or simply and intermittent wheel sensor?

Answer
If the ABS chatters and the car keeps rolling there is probably a sensor problem.  The only way to know would be to look at the live data and faults with the T4 or Autologic system.  You could pull out the sensors and make sure they are clean and seated. You can also make sure the hub bearings are tight.  That's kind of it for home service on that system